Koln vs Cologne

Koln and Cologne both are nouns.

Word	Noun	Adjective	Verb	Adverb
Koln	Yes	No	No	No
Cologne	Yes	No	No	No

As nouns, Koln and Cologne are synonyms defined as:

Koln and Cologne: a commercial center and river port in western Germany on the Rhine River; flourished during the 15th century as a member of the Hanseatic League

Koln (noun)	Cologne (noun)
a commercial center and river port in western Germany on the Rhine River; flourished during the 15th century as a member of the Hanseatic League	a commercial center and river port in western Germany on the Rhine River; flourished during the 15th century as a member of the Hanseatic League