Dual Layer DVD question please help (pics inside)

Here is a pic explaining what I can and cant do.. I cant understand the + and the -
So Here is the pic... I want to beable to burn dual layered DVD's to make a backup copy for a XBOX game.

 

You can use dvd+R dual layer to burn your game

 

any suggestions for good dvd DL's?

 

1) Verbatim 2.4x +R, Made in Singapore
2) Ritek, Ridata 2.4x +R, Made in Taiwan