load up vs overcharge

load up is not a noun while overcharge is a noun.

Word	Noun	Adjective	Verb	Adverb
load up	No	No	Yes	No
overcharge	Yes	No	Yes	No

As verbs, overcharge is a hyponym of load up; that is, overcharge is a word with a more specific, narrower meaning than load up:

Other hyponyms of load up include load down, pack, bomb up, overload, surcharge, reload, stack.

load up (noun)	overcharge (noun)
	a price that is too high

load up (verb)	overcharge (verb)
fill or place a load on	place too much a load on
	rip off; ask an unreasonable price