A criminal is someone who has broken the laws of man, nature, religion or government while in a state of mind that they knew that they were doing wrong. A criminal, as defined by the stautes of criminal law, has been tried in a court of law by an assembly of their peers, or a duly appointed judge, and found guilty of the crime that they were accused of committing. Punishment has nothing to do with the labelling of criminal on a person, as many people get probation, house arrest or even sentenced to time served while awaiting trial or in the county lockup after arrest.
A criminal is not defined by the laws that they break, or by their age (although many States and Provinces, in the USA and Canada, do not prosecute people under 7 years of age for any crimes), since a shoplifter from Boise, Idaho would retain the moniker of criminal the same as the Bernie Madoffs out there, bilking friends and acquaintances for billions of dollars (50 of them, to be exact!) with darling deals that turn out to be ponzi schemes. Nor is a criminal defined by the way they look, the way they act or the way they talk, unless, of course, those actions and speeches are against the law. Looking like Richard Simmons may seem like it should be illegal, but it is not criminal, in the true context of the word at least.
Criminal defined can also be "shameful, unwise or regrettable" (Windows Dictionary), as in "a criminal waste of taxpayer's money went to the automotive industry executives". The civilian, politician or government branch that misspent the money is not a criminal, but they did not pay due diligence and work with the best interests of the money's owners in mind. This can make them a "moral criminal", and that would have to be worked out between them and their God after they die.
The scale of the crime committed in making the criminal out of the law abiding citizen does not affect the fact that a crime was committed, found out and acted upon by the requisite law enforcement agencies. Criminal defined does not necessarily imply that the accused person had actually broken a law, only that they were charged and found guilty of a crime. A real criminal is a person who breaks laws willingly, whether or not they care about their victims' plights not withstanding. A person selling crack cocaine on a street corner across from a public school is a criminal in everyone's eyes, but a marine killing an innocent civilian while carrying out his orders may be a hero to some, a criminal to others.
A person caught with a small amount of marijuana in their possession could get anywhere from a small fine to life imprisonment as punishment, depending upon where they were caught (you do not want to get caught with any amount of marijuana in Nevada, the "zero tolerance State"), and in some cases the circumstances under which they were caught. However, no matter the sentence, the moniker of criminal will stay with the person until they have applied for and have been granted a full pardon and had their records expunged.
In one country a person may be considered a criminal, and be considered a hero in another country for the same illegal act. One person's martyrdom is another person's terrorist act. Whether the person had intention to break the law can also have an effect on their being classified as a criminal defined as the law breaker, as opposed to the criminal defined as the breaker of moral judgement.
When found not criminally responsible by means of mental disease or defect, then a person who committed even the most heinous of acts may be forgiven the moniker of criminal, even though the action is criminal defined in every aspect of the word.