It's my understanding that the main difference at SSR is that the studios have one double bed and a pull out sofa.
So if you have a lock off 2 BR, in one of the bedrooms (the studio part) you will only have one double bed and one pull out sofa).
In the dedicated 2 bedroom, the second bedroom will have 2 double beds.
Since I have 2 kids (a 20 year old girl and an 18 year old boy) I need 2 beds, one for each.