like thunder vs like mad

like thunder and like mad both are adverbs.

Word	Noun	Adjective	Verb	Adverb
like thunder	No	No	No	Yes
like mad	No	No	No	Yes

As adverbs, like thunder and like mad are synonyms defined as:

like thunder and like mad: (informal) with great speed or effort or intensity; used for emphasis

Other synonyms of like thunder include like crazy, like hell, like sin, like the devil.

like thunder (adverb)	like mad (adverb)
(informal) with great speed or effort or intensity; used for emphasis	(informal) with great speed or effort or intensity; used for emphasis