The drug itself is finasteride. Propecia is the brand name of a 1mg finasteride pill. Proscar is the brand name of a 5mg finasteride pill. Getting generics just means you're getting finasteride from some random pharmaceutical lab instead of the company that originally had a patent on the drug...
I have used both generic and propecia. Noticed zero difference..! I've been on generic finasteride for almost a year now. I have had zero sides. Actually I use Proscar and I have great results with generic.