item vs portion

item and portion both are nouns.

Word	Noun	Adjective	Verb	Adverb
item	Yes	No	No	Yes
portion	Yes	No	Yes	No

As nouns, portion is a hypernym of item; that is, portion is a word with a broader meaning than item:

item: a distinct part that can be specified separately in a group of things that could be enumerated on a list
portion: something determined in relation to something that includes it

Other hypernyms of item include component, component part, constituent, part.

As nouns, portion is a hypernym of item; that is, portion is a word with a broader meaning than item:

Other hypernyms of item include component, component part, constituent, part.

item (noun)	portion (noun)
a whole individual unit; especially when included in a list or collection	the allotment of some amount by dividing something
an isolated fact that is considered separately from the whole	something less than the whole of a human artifact
a distinct part that can be specified separately in a group of things that could be enumerated on a list	an individual quantity of food or drink taken as part of a meal
an individual instance of a type of symbol	assets belonging to or due to or contributed by an individual person or group
a small part that can be considered separately from the whole	money or property brought by a woman to her husband at marriage
	something determined in relation to something that includes it
	your overall circumstances or condition in life (including everything that happens to you)

item (verb)	portion (verb)
	give out

item (adverb)	portion (adverb)
(used when listing or enumerating items) also