ski parka vs ski jacket

ski parka and ski jacket both are nouns.

Word	Noun	Adjective	Verb	Adverb
ski parka	Yes	No	No	No
ski jacket	Yes	No	No	No

As nouns, ski parka and ski jacket are synonyms defined as:

ski parka (noun)	ski jacket (noun)
a parka to be worn while skiing	a parka to be worn while skiing