like a shot vs immediately

like a shot and immediately both are adverbs.

Word	Noun	Adjective	Verb	Adverb
like a shot	No	No	No	Yes
immediately	No	No	No	Yes

As adverbs, like a shot and immediately are synonyms defined as:

like a shot and immediately: without delay or hesitation; with no time intervening

Other synonyms of like a shot include at once, directly, forthwith, instantly, now, right away, straight off, straightaway.

like a shot (adverb)	immediately (adverb)
without delay or hesitation; with no time intervening	without delay or hesitation; with no time intervening
	near or close by
	bearing an immediate relation