professional vs semipro

professional and semipro both are nouns.

Word	Noun	Adjective	Verb	Adverb
professional	Yes	Yes	No	No
semipro	Yes	No	No	No

As nouns, semipro is a hyponym of professional; that is, semipro is a word with a more specific, narrower meaning than professional:

Other hyponyms of professional include free agent, semiprofessional.

professional (noun)	semipro (noun)
a person engaged in one of the learned professions	an athlete who plays for pay on a part-time basis
an authority qualified to teach apprentices
an athlete who plays for pay

professional (adjective)	semipro (adjective)
engaged in a profession or engaging in as a profession or means of livelihood
characteristic of or befitting a profession or one engaged in a profession
of or relating to a profession
of or relating to or suitable as a profession
engaged in by members of a profession