0 Minecraft Windows 10 Edition?

My sister has wanted Minecraft for the PC for a while now. She played the free beta of the windows 10 edition, and now wants top buy it. Is it worth it to buy the original version from Mojang? I don't know what the differences are between the versions, if there are any. All I now is that the original has an extra $15 to the price tag. Is there more to that version? Will my system be able to handle it if the windows 10 free version worked fine? She is also talking about mods, which i don't know if my system can handle those, either (I use a laptop for stuff, atm).

I saw somewhere on the store (can't remember where) it said if you have the standard version, you can get the Windows 10 version for free, is this true, or did I imagine it?

Thanks!

Added (1). Also, can she play with Xbox users with the Windows 10 version?

Get the original version and you'll get the Windows 10 Edition free. Yes, your PC will run the original if it runs the Windows 10 edition.

The Windows 10 Edition will eventually have the same features as the original Java edition but until then the original will be the better of the two as far as features go.