soda water vs soda pop

soda water and soda pop both are nouns.

Word	Noun	Adjective	Verb	Adverb
soda water	Yes	No	No	No
soda pop	Yes	No	No	No

As nouns, soda water and soda pop are synonyms defined as:

soda water and soda pop: a sweet drink containing carbonated water and flavoring

Other synonyms of soda water include pop, soda, tonic.

soda water (noun)	soda pop (noun)
effervescent beverage artificially charged with carbon dioxide	a sweet drink containing carbonated water and flavoring
a sweet drink containing carbonated water and flavoring