ok the description says it plays dvd-r's will it work on a dvd+r? whats the difference

I am assuming you are talking about the no solder mod. It will play +r if your laser is up to the task. Some v4s play +r, some don't.

okay so if what you are saying is going through my head right...some lasers are stroonger than others?

Correct. v1-v3 sucked. v4 was so so. v5 and up are best.