meaningof stud bolt, hex bolt and shackle bolt.?

Question

with ref to auto spare parts

Answer 1

I was about to let you know about the bolts, but William B already gave a good answer. The only thing I might add would be that some shackle bolts look like U bolts with squared off corners instead of round.
Good luck with whatever endeavor prompted this question.
dd

Answer 2

a stud bolt is threaded on both ends,
a hex bolt has a hex head on it, so a wrench can turn it,
a shackle bolt is a bolt that has a tinsel strength for closing shackles,