group vs chunk

group and chunk both are nouns.

Word	Noun	Adjective	Verb	Adverb
group	Yes	No	Yes	No
chunk	Yes	No	Yes	No

As verbs, chunk is a hyponym of group; that is, chunk is a word with a more specific, narrower meaning than group:

Other hyponyms of group include regroup, bracket, collocate, lump, batch.

group (noun)	chunk (noun)
any number of entities (members) considered as a unit	a compact mass
a set that is closed, associative, has an identity element and every element has an inverse	a substantial amount
(chemistry) two or more atoms bound together as a single unit and forming part of a molecule

group (verb)	chunk (verb)
arrange into a group or groups	group or chunk together in a certain order or place side by side
form a group or group together	put together indiscriminately