tight fitting vs tightly fitting

tight fitting and tightly fitting both are adjectives.

Word	Noun	Adjective	Verb	Adverb
tight fitting	No	Yes	No	No
tightly fitting	No	Yes	No	No

As adjectives, tight fitting and tightly fitting are synonyms defined as:

Other synonyms of tight fitting include skinny, tight-fitting, tightfitting.

tight fitting (adjective)	tightly fitting (adjective)
fitting snugly	fitting snugly