German vs Boche

German and Boche both are nouns.

Word	Noun	Adjective	Verb	Adverb
German	Yes	Yes	No	No
Boche	Yes	No	No	No

As nouns, Boche is a hyponym of German; that is, Boche is a word with a more specific, narrower meaning than German:

Other hyponyms of German include Teuton, East German, Hun, Jerry, Kraut, Krauthead, Berliner, Prussian, Bavarian.

German (noun)	Boche (noun)
the standard German language; developed historically from West Germanic	offensive term for a person of German descent
a person of German nationality

German (adjective)	Boche (adjective)
of or pertaining to or characteristic of Germany or its people or language