portmanteau vs Gladstone bag

portmanteau and Gladstone bag both are nouns.

Word	Noun	Adjective	Verb	Adverb
portmanteau	Yes	No	No	No
Gladstone bag	Yes	No	No	No

As nouns, portmanteau and Gladstone bag are synonyms defined as:

portmanteau and Gladstone bag: a large travelling bag made of stiff leather

Other synonyms of portmanteau include Gladstone.

portmanteau (noun)	Gladstone bag (noun)
a large travelling bag made of stiff leather	a large travelling bag made of stiff leather
a new word formed by joining two others and combining their meanings