aristocracy vs elite group

aristocracy and elite group both are nouns.

Word	Noun	Adjective	Verb	Adverb
aristocracy	Yes	No	No	No
elite group	Yes	No	No	No

As nouns, elite group is a hypernym of aristocracy; that is, elite group is a word with a broader meaning than aristocracy:

aristocracy: a privileged class holding hereditary titles
elite group: a group or class of persons enjoying superior intellectual or social or economic status

Other hypernyms of aristocracy include elite.

aristocracy (noun)	elite group (noun)
a privileged class holding hereditary titles	a group or class of persons enjoying superior intellectual or social or economic status
the most powerful members of a society