pitsaw vs two-man saw

pitsaw and two-man saw both are nouns.

Word	Noun	Adjective	Verb	Adverb
pitsaw	Yes	No	No	No
two-man saw	Yes	No	No	No

As nouns, two-man saw is a hypernym of pitsaw; that is, two-man saw is a word with a broader meaning than pitsaw:

pitsaw: a large two-handed saw formerly used to cut logs into planks; one man stood above the log and the other in a pit below
two-man saw: a saw with handles at both ends; intended for use by two people

Other hypernyms of pitsaw include lumberman's saw, two-handed saw, whipsaw.

pitsaw (noun)	two-man saw (noun)
a large two-handed saw formerly used to cut logs into planks; one man stood above the log and the other in a pit below	a saw with handles at both ends; intended for use by two people