Dont feel bad about your question. It took me a while to understand this myself.
Propecia and Proscar are both the same drug. The main ingredient in both is finasteride. They are both made by Merck.
1mg of finasteride is recommended for hair loss.
5mg of finasteride is recommended to deflate an enlarged prostate gland.
If you take a 5mg Procar pill and cut it into 5 little pieces they each equal 1 Propecia each.
If you take 5 pills of 1mg Propecia it equals 1 Proscar pill.