hob vs shelf

hob and shelf both are nouns.

Word	Noun	Adjective	Verb	Adverb
hob	Yes	No	Yes	No
shelf	Yes	No	No	No

As nouns, shelf is a hypernym of hob; that is, shelf is a word with a broader meaning than hob:

hob (noun)	shelf (noun)
a shelf beside an open fire where something can be kept warm	a support that consists of a horizontal surface for holding objects
a hard steel edge tool used to cut gears	a projecting ridge on a mountain or submerged under water
(folklore) a small grotesque supernatural creature that makes trouble for human beings
(folklore) fairies that are somewhat mischievous

hob (verb)	shelf (verb)
cut with a hob