Most gamblers are social gamblers.

Gambling is one of many forms of entertainment they engage in, it is not their main recreational activity.

They rarely think about gambling.

Gambling episodes are usually infrequent, but there may be some regular activity as well (e.g., a monthly poker game, an occasional vacation to Vegas, a weekly or even daily lottery ticket). 

Gambling does not result in any negative life-consequences.

There is no loss of control over gambling duration, frequency or money spent (sometimes there might be one episode of this).

They would not be upset if unable to gamble ever again.

There are no lasting negative financial consequences as a result of the gambling.

There are no attempts to hide any aspect of the behavior.

Other people do not see their gambling as excessive.

Gambling is an important part of their lives and would missed if they could not engage in it. 

There may be an intense focus on a single form of gambling (e.g., horse racing, poker, sports betting).

There is no loss of control over wager amount or frequency.

No progressive increase in wager size over time.

No financial strain due to gambling, money for retirement, family, health, etc. is not being diverted 

Money is not borrowed from any source (including credit cards).

Gambling is generally not viewed as a way to pay for basic life necessities or luxuries.

No relationship arguments or relationship problems occur due to gambling.

Gambling does not diminish their work performance or focus.

Wager size is responsible and reasonable for the person's income.

Relationships with family members and friends are not diminished due to time spent gambling.

The time spent gambling appears reasonable to an outsider.

The gambler does not chase losses.

There are not mood swings associated with the wins and losses.

The gambler remains interested in non-gambling activities and engages in them frequently.

Non-gambling friends and activities are plentiful.

Problem and pathological gamblers often minimize their situation to try and appear like frequent gamblers.

A frequent gambler may eventually advance into problem or pathological gambling

If a gambler is affluent the distinction between frequent and problem gambling is somewhat more complicated. 

Gambling results at least one negative consequence to the gambler or person in their life, this would include relationship problems.

Money used to gamble with should be otherwise allocated to other things.

There might be family discord regarding the time or amount spent gambling.

The gambling may diminish work performance or ability to focus on work fully.

Long term goals and ambitions are sometimes replaced by gambling.

Usually the gambler can and does quit or stop for periods of time, and may do so to "prove" that they do not have a problem.

Often there is some degree of intolerance to losing as demonstrated by mood swings after a loss, or chasing the loss to get even.

Problem gamblers may deny that any problem is occurring despite the observations of others.

There may be attempts to hide or minimize gambling behavior.

Often thinks of gambling as a second job or a viable source of revenue; they may aspire to be professional gamblers.

May try to earn money needed for daily living by gambling, and in the process get into financial jams.

Time spent gambling exceeds what an outsider would think is reasonable.

Unless the gambler is affluent, money may be occasionally borrowed from other people or credit cards.

Problem gamblers often temporarily quit gambling after a big loss and will resume once their finances have stabilized. 

Often viewed as being a "regular" at gambling establishments, staff may know their name and they receive comps, these comps, or other reward programs foster more gambling.

The severity of the problem does not meet the full criteria for a diagnosis of pathological gambling as defined in the Diagnostic and Statistical Manual of Psychiatry, DSM-IV™ (a copy is provided in the assessment section) but they often have between 1 and 3 symptoms.  

This is the only "type" of gambler that has been fully defined by the American Psychiatric Association as a mental disorder.

Usually has had at least one financial bailout from a friend, family member, maxed out credit cards or taken out loans from financial institution,  unless they are affluent, although some pathological gamblers never have had a bailout.

Pathological gamblers share some of the symptoms that are evidenced in problem gamblers (see above list).

There may be attempts to justify, rationalize, hide, and/or minimize their behavior to others.

Often they will mis-conceptualize the gambling problem as a financial problem.

May blame others for stress they are creating.

May try to win money needed for basic living expenses.

Winning means more time to gambling, wins are usually "re-invested" into more gambling.

Usually thinks that they are only hurting themselves, unaware of the impact of their gambling on others.

Wager size increases over time (measured usually in years).

Uses money to gamble that should otherwise be allocated/invested; for example does not have a independent retirement plan (e.g., IRA) that not associated with their work plan (e.g., 401K).  This would not apply to some people.

Gambling does not have to be daily in order for it to be pathological.

Engages in "creative financing" by obtaining loans and credit.

May have burned out relationships due to gambling and borrowing.

Unable to easily quit gambling for long periods of time.

May promise self or other to quit gambling after a large loss or win, but can't or doesn't for long.

May feel urges and cravings to go gamble.

Frequent fights with spouse/partner, blames them for the problems.

Feels excited when gambling or about to gamble, might have a rush just walking into gambling establishment.

Gambling establishments may feel like "coming home" when they enter after an absence.

Other gambling patrons or more likely casino staff are thought of as "friends" despite a lack of connection outside of the gambling venue, although this is not very common.

The solution to financial problems and stress created by gambling is to gamble more in order to finally hit a big win, or at least recover losses.  Thus the problem also is seen as the solution, a characteristic of addiction.

A Pathological gambler meets the criteria for the disorder as listed in the as defined in the Diagnostic and Statistical Manual of Psychiatry, DSM-IV™ (a copy is provided in the assessment section). 

I have had many severely disordered gamblers that would adamantly state that they are not compulsive or pathological. 

Rarely loses control when placing bets.

Gambling is methodical and planned (e.g., a professional horse gambler may not bet on every race). 

Maintain discipline and refrain from impulsive betting

Accept financial losses without chasing to win them back.

Professional gamblers do not meet the DSM-IV criteria for pathological gambling, but may have a couple of symptoms (e.g. preoccupation).  

Gambling is their primary source of income.  

Most problem and pathological gamblers fantasize about being a professional gambler or mistakenly believe that they are, there are very few true professional gamblers.

Many professional gamblers will eventually evolve in to problem or pathological gambling. 

It has been estimated that there are fewer than 3,000 professional gamblers in the US and Canada and only 50 professional gamblers in the U.S. who earn over $100,000 dollars annually by gambling.  Psychological profiles of professional horse gamblers showed they tend to be somewhat boring, socially insensitive, extremely unsentimental, hyper-vigilant, and very tense. (McCown & Chamberlain, 2000).

The term "professional gambler" is very complex in distinguishing from problem and pathological gambler and the assessment should be conducted by a trained professional therapist who also consults with the gambler's family/friends regarding the presence of symptoms. 

A win creates a "rush" that is probably associated with an excessive release of the neurotransmitter dopamine.  Dopamine is a brain chemical associated with the subjective experience of pleasure.     

Reacts to gambling with an unusual degree of excitement, although this may experienced by the gambler but not expressed.

More often plays games such as cards, craps, roulette, sports betting.

A win may lead to larger bets.

Gambling excitement is extremely pleasurable and achieving it becomes a major focus in the gambler's life.

More men are action gamblers than women

Often associated with ambitious, high intelligence, Type-A, "driven to succeed" personality traits.

Besides gambling in a habitual pattern, they are more likely than the escape gambler to bet when feeling good, happy or lucky.

Engages in criminal activities, scams and rip-offs.

Gambling is a method to steal money, may use loaded dice, marked cards, and fixed sports events or horse races.

Different from gamblers who commit a crime to pay debt.

May have a diagnosis of Antisocial Personality Disorder