work on vs cold work

work on and cold work both are verbs.

Word	Noun	Adjective	Verb	Adverb
work on	No	No	Yes	No
cold work	No	No	Yes	No

As verbs, cold work is a hyponym of work on; that is, cold work is a word with a more specific, narrower meaning than work on:

Other hyponyms of work on include hot-work, coldwork, overwork, make over, retread, rework, rack, tool, till.

work on (verb)	cold work (verb)
shape, form, or improve a material	shape (metal) without heat
to exert effort in order to do, make, or perform something