Yup. "Shock" is a verb--it's what you do (not that it actually means much).

When you "shock" a pool, you are simply upping the chlorine in it to a level that will kill anything in it.

Bleach is Liquid Chlorine in either 5.25% or 6% concentrations. The first is called "regular" the second "ultra". "Liquid Shock" at the pool store is Liquid Chlorine in 6%, 10% or 12.5% concentrations. (Technically, Sodium Hypochlorite diluted in Sodium Chloride solution, ie, saltwater).

Packets labeled "shock" are usually convenient-sized but expensive packs of Di-Chlor, Tri-Chlor, Calcium Hypochlorite, or Lithium Hypochlorite (this last is insanely expensive). They all do the same thing as Liquid Chlorine/Bleach: Raise your chlorine level in your pool to where it kills living stuff and metabolizes other stuff (like sun-tan lotion).

But they all have drawbacks.
Di-Chlor and Tri-chlor add stabilizer, which you may or may not want. They both lower pH, though Tri-chlor does it more dramatically.

Cal-Hypo is trickier to handle, quite dangerous around other forms of chlorine when it's in effective concentrations (over 60%), adds calcium, which you DON'T want in a vinyl pool and MAY want more of in a concrete pool, and may raise your pH and be tough to dissolve.

Lithium is insanely expensive for fairly low concentrations.

ONCE they are dissolve in the water, they are all the same--chlorine is chlorine is chlorine.

But each can be beneficial. I'm using Tri-Chlor right now since my pH was fairly high, my CYA(stabilizer) was non-existent, and I had just trounced the biggest algae bloom I ever had, and the first at spring opening, so I wanted a constant chlorine level. Once I hit my target CYA, I'll stop--or when the last tablets dissolve!