Differences between lua 5.1 and 5.2?

I was thinking about adding OpenComputers into my modpack to see the differences between it and ComputerCraft.

Just wanting to know what lua 5.2 adds that 5.1 does not.

Like, if I have lua 5.1 and lua 5.2 on my pc (Not talking about minecraft, talking about compiling with Cygwin), could I be able to paste some 5.1 lua into the 5.2 console and still have it run normally?

also I have heard there's a lua 5.3 now, what got added/removed in that?

I only understand updates if it is in big bold letters like this.

See here, I guess.

If you paste Lua 5.1 specific code into a 5.2 environment, or vice versa, then certainly it's going to have problems. Whether a given script contains code "specific" to a given version of Lua depends on how it's written. Your average "hello world!" script, for example, is unlikely to encounter any difficulties.

Okay I'm just not going to get OpenComputers, The only 2 scripting languages I wan't to know is lua and python. lua 5.1 to be exact.