part-time vs half-time

part-time and half-time both are adjectives.

Word	Noun	Adjective	Verb	Adverb
part-time	No	Yes	No	Yes
half-time	No	Yes	No	Yes

As adverbs, part-time and half-time are synonyms defined as:

Other synonyms of part-time include parttime.

part-time (adjective)	half-time (adjective)
involving less than the standard or customary time for an activity	involving half the standard or customary time for an activity

part-time (adverb)	half-time (adverb)
for less than the standard number of hours	for less than the standard number of hours