transgressor vs offender

transgressor and offender both are nouns.

Word	Noun	Adjective	Verb	Adverb
transgressor	Yes	No	No	No
offender	Yes	No	No	No

As nouns, offender is a hypernym of transgressor; that is, offender is a word with a broader meaning than transgressor:

transgressor: someone who transgresses; someone who violates a law or command
offender: a person who transgresses moral or civil law

Other hypernyms of transgressor include wrongdoer.

transgressor (noun)	offender (noun)
someone who transgresses; someone who violates a law or command	a person who transgresses moral or civil law