tourist class vs third class

tourist class and third class both are nouns.

Word	Noun	Adjective	Verb	Adverb
tourist class	Yes	No	No	No
third class	Yes	No	No	No

As nouns, tourist class and third class are synonyms defined as:

tourist class and third class: inexpensive accommodations on a ship or train

tourist class (noun)	third class (noun)
inexpensive accommodations on a ship or train	inexpensive accommodations on a ship or train
	mail consisting of printed matter qualifying for reduced postal rates