react vs act on

react and act on both are verbs.

Word	Noun	Adjective	Verb	Adverb
react	No	No	Yes	No
act on	No	No	Yes	No

As verbs, act on is a hyponym of react; that is, act on is a word with a more specific, narrower meaning than react:

Other hyponyms of react include follow up on, pursue, buck, go against.

react (verb)	act on (verb)
undergo a chemical reaction; react with another substance under certain conditions	carry further or advance
show a response or a reaction to something	regulate one's behavior in accordance with certain information, ideas, or advice
act against or in opposition to