Preussen vs Prussia

Preussen and Prussia both are nouns.

Word	Noun	Adjective	Verb	Adverb
Preussen	Yes	No	No	No
Prussia	Yes	No	No	No

As nouns, Preussen and Prussia are synonyms defined as:

Preussen and Prussia: a former kingdom in north-central Europe including present-day northern Germany and northern Poland

Preussen (noun)	Prussia (noun)
a former kingdom in north-central Europe including present-day northern Germany and northern Poland	a former kingdom in north-central Europe including present-day northern Germany and northern Poland