Urdu/Hindi share a grammatical system that is extremely similar to Punjabi. A lot of the vocabulary is the same too, but some of it might be pronounced differently. If your familiar with grammar in a language similar to Punjabi (any language based off Sanskrit) then just focus on Punjabi vocabulary, cause the grammar will be easy.

Thanks for your help waleed!

Yes they are pretty much the same. But that can also be a problem for a beginner. You can easily mix up the words and different terms. So i would advise that you should get a good control on one of them, and after that it would be easy for you to learn the other.