Difference between Obligatory and Necessary

Obligatory

Part of speech: adjective

Definition: Imposing obligation, morally or legally; binding: an obligatory promise. Requiring a matter or obligation.

Necessary

Part of speech: noun

Definition: bathroom, toilet, loo

Part of speech: adjective

Definition: needed, required

Example sentence: Government, even in its best state, is but a necessary evil; in its worst state, an intolerable one.