load up vs overload

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

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

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

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

load up (noun)	overload (noun)
	an excessive burden
	an electrical load that exceeds the available electrical power

load up (verb)	overload (verb)
fill or place a load on	fill to excess so that function is impaired
	place too much a load on
	become overloaded