In general, the difference here (if we are talking about sociology) is that diversity is used to refer to group characteristics while deviance is used to refer to behaviors. This is not 100% true, but it is the general difference between the two.
Diversity tends to refer to things such as differences of race, class, or culture. These are things that typify a group. These sorts of differences do not have a moral value to them -- they are simply ways in which people are different. By contrast, deviance refers to behaviors that are seen by the society as wrong. This includes things such as crime, but it also includes behaviors that are simply seen as immoral (though not criminal).
There are some instances in which it is hard to tell the two apart and in which classifying something as deviance or diversity is a political or ideological issue. The most obvious of these is homosexuality -- is this something that is value neutral (diversity) or is it deviant?
deviance is violating social norm, breaking rules of society. and diversity is variation of things, like culture and beliefs. so Deviance means can be different in diversity of culture or beliefs. for example, for American culture having kids before gettng marry isnt deviance, but for eastern culture it is a very deviant act. this example is using diversity of american and eastern cultural.
Diversity- range of different things. E.g. diversity of cultures, beliefs etc
Deviance- an off-shoot of the norm. Normally this has a negative connotation because it does not fit into black and white; it creates grey areas.