Hello everyone! :3 I know this beta is a bit old now (two years) but there is always someone who is new to it. I made a .txt file with all the differences I manage to found out (maybe I slipped one or two, sorry :s) but everything you need to know is there. Sorry for my english, I'm not from USA, but I'm studying to become an english teacher someday!
I tried uploading the .txt file, but it can only be uploaded in a .zip archive, but it is too big, so I uploaded it to Mega.

https://mega.co.nz/#!ad9WEZoL!j5Vb9toVJ-4Hr5edWAqWBXKuXEuEXBjfnUCnTahw-xE

I downloaded it from here:
http://coolrom.com/roms/psx/40138/Twisted_Metal_2_(Beta).php

Also, Sweet Tooth does have passwords in the beta version, but these aren't working at all.