on time vs punctual

on time and punctual both are adjectives.

Word	Noun	Adjective	Verb	Adverb
on time	No	Yes	No	Yes
punctual	No	Yes	No	No

As adjectives, on time and punctual are synonyms defined as:

on time and punctual: acting or arriving or performed exactly at the time appointed

on time (adjective)	punctual (adjective)
acting or arriving or performed exactly at the time appointed	acting or arriving or performed exactly at the time appointed
payable in installments within a designated period of time

on time (adverb)	punctual (adverb)
at the expected or proper time