Glock 30 gen 3 or gen 4.

I went to the dealer to look at a glock 30 gen 3. I wanted it but they didn't have the blue label glock 30 and I was not going to pay full price since they offer the discount to military. They let me fill out my background check without purchasing a gun. They said they would contact glock and get it shipped to me. Well they just called and told me that a distributor has a gen 4 glock 30 and they wanted to know if I would be interested in that instead, they said it was the same price and could have it shipped overnight. What is the difference between the two and which in your opinion is better? Does the gen 4 usually cost more? Are they giving me a deal or is the older gen 3 a per say better pistol? I told them to have the gen 4 shipped but I want everyone's opinion before I purchase. Any thoughts would be appreciated. I apologize for the long write up. Thanks in advance.