Bromo-seltzer vs alkaliser

Bromo-seltzer and alkaliser both are nouns.

Word	Noun	Adjective	Verb	Adverb
Bromo-seltzer	Yes	No	No	No
alkaliser	Yes	No	No	No

As nouns, alkaliser is a hypernym of Bromo-seltzer; that is, alkaliser is a word with a broader meaning than Bromo-seltzer:

Bromo-seltzer: an antacid
alkaliser: an agent that counteracts or neutralizes acidity (especially in the stomach)

Other hypernyms of Bromo-seltzer include alkalizer, antacid, antiacid, gastric antacid.

Bromo-seltzer (noun)	alkaliser (noun)
an antacid	an agent that counteracts or neutralizes acidity (especially in the stomach)