Hi Jdub...
I saw your other thread and I've responded there also but I'll give you my opinion since I know this will be your first Android phone.......
First Opinion...Don't worry about it...is my advice.

Since you're totally new to Android then either one would be a learning curve for you...so I say...go with your gut haha.
Use your 14 day trial to choose one of those phones....or if you go to Costco you technically have a 30 day trial. Plenty o time, IMO.

You never know, you might not like Android at all.
Unless you really really want my honest opinion, I would go with the Gnex. It's more expensive and you might not be used to the size compared to the Iphone
but the OS that the Gnex is running is the future of Android phones. Might as well get used to it if you plan to stay with an Android phone because most of the newer phones like the Bionic will be getting ICS.
Worse case scenario, you don't like the Gnex but then you'll get all of your money back or choose another phone like the bionic and get some of your money back. Both phones are better than the Iphone4, IMO.
At least that's how I would look at it.