It may be tempting to think that some terms used in language are synonyms; that it is a case of 'six of one and half a dozen of the other'. The difference between the terms 'crazy' and 'eccentric' may seem like a trivial issue. However, in the realm of psychology, this has far-reaching implications. Even in a non-technical language, the difference between 'crazy' and 'eccentric' is significant.
In language, 'crazy' is a broad term that can denote madness or extreme enthusiasm. 'Eccentric' refers to oddity. The terms may seem related because they are. However, it is because they both attempt to describe deviations from what people consider 'normal behaviour' to be. Normal behaviour is subjective and different within and across cultures.
'Crazy' is sometimes used in a non-pejorative sense (extreme enthusiasm). In that case, it is different from eccentricity because the term 'eccentric' describes an enduring quality. 'Crazy' in the sense of madness refers to either a temporary or a permanent state of being. However, being odd (eccentric) or 'crazy' (in either sense) denote alternative states of being.
To demonstrate the difference, it is necessary to look at abnormal behaviour is two ways. Eccentricity describes behaviour that deviates from accepted norms within a defined culture or statistically infrequent behaviour. The term 'crazy'- in the sense of madness- suggests maladaptive behaviour (inability to function properly). In psychological terms, 'crazy' describes maladaptive behaviour and not extreme enthusiasm. Therefore, the terms 'crazy' and 'eccentric' deal with different aspects of abnormal behaviour.
An eccentric person and a crazy person may be treated differently as well. An eccentric may have issues adjusting socially or 'fitting in'. However, madness affects an individual's psychological and social functioning. To demonstrate the cogent distinction between the two terms, an eccentric person may seek counselling (if their eccentricity affects them) while a person diagnosed as crazy (or suspected to be crazy) needs psychiatric help or a psychiatric evaluation.
The difference between the two terms is also an issue of labelling. 'Crazy' is a more pejorative term than eccentric- even though some persons try to use the word 'crazy' in a neutral way. Persons labelled as 'crazy' are unlikely to be taken seriously or be perceived as though something is wrong with them. Persons labelled as 'eccentric' are likely to be regarded as 'special', 'unique' or 'weird' (at worst). How a person understands the terms 'crazy' and 'eccentric' determine how they treat with someone labelled as either.
Clearly, the terms 'crazy' and 'eccentric' are not synonyms and should not be used interchangeably. Referring to someone (or yourself) as 'crazy' when you mean 'eccentric' could negatively influence perceptions, especially where shared meanings of the words do not exist. While the two terms describe abnormal behaviour, they have different implications- even beyond the realm of psychology.