Your Gmail is your Google account. So you only need your Gmail to access the Market.
I have had a Google account for many years without a Gmail account.
Anyway, I did find out a couple of things which are different for the Android devices which do not come with a Phone Service.
Since the Samsung Galaxy 5.0 Player does not come with a Telephone Service Provider there are a couple of things which are different when trying to get it set-up. Especially if you have never used an Android Device before.
With no service provider for the Samsung Galaxy 5.0 Player you do have to set-up both a Google and Gmail Accounts. Then the device has to be linked to the Google Account before it will allow the installation of any apps. There was a screen that popped up on the Galaxy which I had not seen before, while I was searching for a way to download the apps. which allowed me to link my Device to the Google Account.
After accomplishing the Link with my Google Account installing apps was no problem.
According to my son, who has an Android Cell Phone, he never had to go through any of the steps I was required to, to download/install apps.
So, it appears this new version of Android device, which comes without a specific Phone Service with built-in app support, we do have to take a couple of extra steps to fully use our devices.