In which context are these two words used?

Abstemious & Abstinent

The adjective abstemious means 'sparing in consumption of food and drink, not self-indulgent'. The word comes from the Latin abstemius from ab-, abs-, 'away from' + temetum, 'alcoholic drink'. Abstinent comes from a different Latin word, abstinere, 'to abstain', from ab-, abs-, 'away from', + tenere, 'to hold'. It means 'denying one's appetites completely; doing without'.

Abstinent differs from abstemious in two respects: first, it refers to all appetites and desires, whereas abstemious tends to refer only to food and drink, or even specifically to alcoholic drink alone; secondly, abstinent suggests total self-denial, abstemious simply suggests moderation. 

The noun derived from abstemious is abstemiousness; abstinent has two related nouns-abstinence and abstention. Abstention, unlike abstinence, has no suggestion of denying the appetites: it refers simply to refraining from something-a single act of abstaining(commonly, abstaining from voting). Abstinence suggests continuous abstaining (as from drink).