rainfly vs fly sheet

rainfly and fly sheet both are nouns.

Word	Noun	Adjective	Verb	Adverb
rainfly	Yes	No	No	No
fly sheet	Yes	No	No	No

As nouns, rainfly and fly sheet are synonyms defined as:

rainfly and fly sheet: flap consisting of a piece of canvas that can be drawn back to provide entrance to a tent

Other synonyms of rainfly include fly, tent-fly, tent flap.

rainfly (noun)	fly sheet (noun)
flap consisting of a piece of canvas that can be drawn back to provide entrance to a tent	flap consisting of a piece of canvas that can be drawn back to provide entrance to a tent