dead-man's float vs prone float

dead-man's float and prone float both are nouns.

Word	Noun	Adjective	Verb	Adverb
dead-man's float	Yes	No	No	No
prone float	Yes	No	No	No

As nouns, dead-man's float and prone float are synonyms defined as:

dead-man's float and prone float: a floating position with the face down and arms stretched forward

dead-man's float (noun)	prone float (noun)
a floating position with the face down and arms stretched forward	a floating position with the face down and arms stretched forward