ski jacket vs ski parka

ski jacket and ski parka both are nouns.

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

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

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