Double check buy games site and see if you can find any reviews.
I don't fully understand this but you may have to create a new account for everything you buy on there to use the product
"NO KEY - You will receive an Account that will allow you to download the game. You will be able to play it from your own account, forever.
We offer lifetime warranty for our products. If you cannot access the account you received, we will give you a new one for free. The warranty gets voided if you change the email address or any other info of the account, besides the password."
With CD keys they give you a code to add to the playstation store then that will be added to your personal account as you own it.
The other site looks like you won't actually own it but it will be given under a new PSN account. Similar to netflix shared accounts.