stack vs load up

stack is a noun but load up is not a noun.

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

As verbs, load up is a hypernym of stack; that is, load up is a word with a broader meaning than stack:

Other hypernyms of stack include lade, laden, load.

stack (noun)	load up (noun)
a large tall chimney through which combustion gases and smoke can be evacuated
a storage device that handles data so that the next item to be retrieved is the item most recently stored (LIFO)
a list in which the next item to be removed is the item most recently stored (LIFO)
an orderly pile
(often followed by `of') a large number or amount or extent

stack (verb)	load up (verb)
arrange in stacks	fill or place a load on
load or cover with stacks
arrange the order of so as to increase one's winning chances