sledge vs bobsled

sledge and bobsled both are nouns.

Word	Noun	Adjective	Verb	Adverb
sledge	Yes	No	Yes	No
bobsled	Yes	No	Yes	No

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

sledge: a vehicle mounted on runners and pulled by horses or dogs; for transportation over snow
bobsled: a long racing sled (for 2 or more people) with a steering mechanism

Other hyponyms of sledge include bob, bobsleigh, bobsleigh, dog sled, dog sleigh, dogsled, luge, pung, toboggan.

sledge (noun)	bobsled (noun)
a heavy long-handled hammer used to drive stakes or wedges	a long racing sled (for 2 or more people) with a steering mechanism
a vehicle mounted on runners and pulled by horses or dogs; for transportation over snow	formerly two short sleds coupled together

sledge (verb)	bobsled (verb)
beat with a sledgehammer	ride a bobsled
transport in a sleigh
ride in or travel with a sledge