clustering vs agglomeration

clustering and agglomeration both are nouns.

Word	Noun	Adjective	Verb	Adverb
clustering	Yes	No	No	No
agglomeration	Yes	No	No	No

As nouns, agglomeration is a hypernym of clustering; that is, agglomeration is a word with a broader meaning than clustering:

clustering (noun)	agglomeration (noun)
a grouping of a number of similar things	the act of collecting in a mass; the act of agglomerating
	a jumbled collection or mass