irony vs sarcasm

irony and sarcasm both are nouns.

Word	Noun	Adjective	Verb	Adverb
irony	Yes	No	No	No
sarcasm	Yes	No	No	No

As nouns, irony and sarcasm are synonyms defined as:

Other synonyms of irony include caustic remark, satire.

irony (noun)	sarcasm (noun)
incongruity between what might be expected and what actually occurs	witty language used to convey insults or scorn
a trope that involves incongruity between what is expected and what occurs
witty language used to convey insults or scorn