It's a laptop, so upgrading means changing out parts, not just adding, so no, you won't have room for both. :(
And it's np, I like helping. ^^ Feel free to hit the green "select as best answer button" cause it helps me out too.
Honestly I wouldn't bother with the SSD. Most games don't get much if any loading improvement from having an SSD so you'd only want it for the boot drive, which the Dell already has for you. Spend that money on getting more RAM if anything. If you do want to get the SSD though, check the form...
I'd say go with the dell, it has an SSD for its boot drive so it turns on faster, plus the GPU is the 4g variant.
The asus has a bigger screen and 16gb of memory, but you can upgrade memory in the dell with the money you saved.
Sources...