There are big diffrences, ive started to code it and waiting for a bounty to come for it
A tip would be to watch bubbagame;
http://www.twitch.tv/bubbagame/profile
Ex here:
http://www.twitch.tv/bubbagame/v/5182012
They now send out squares so you can see if the player attacked you, one in your guild or party or none of the above.
Also MWs and wild growths now act like a player, you can walk through them if one in your party or guild threw it (or a player with dove mode).
If you have red mode, cast an MW and then another player walks through it you will be aggressive against that player.
Those are some of the things the new PvP system has, so you need alot of code to fully make it work.
Right now I might have written about 300-500 lines of code to get it semi working.
Still alot to do in the item codes so certain players can walk through it and some can't(depending on PvP mode, damage map etc).
But TFS has not gotten it coded yet, so right now it uses the 8.x PvP system, but not really - I guess we can call it a custom PvP system.