like a shot vs straight off

like a shot and straight off both are adverbs.

Word	Noun	Adjective	Verb	Adverb
like a shot	No	No	No	Yes
straight off	No	No	No	Yes

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

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

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

like a shot (adverb)	straight off (adverb)
without delay or hesitation; with no time intervening	without delay or hesitation; with no time intervening