It depends. Someone has already given the example of the BLT studios being significantly smaller than the CR rooms, which can be a factor. Another one that comes to mind is BCV/BC. Some of the BC rooms have the one person standing balconies and some have full balconies. All of the BCV rooms have full balconies (in fact, I've had some of my largest studio balconies at BCV, depending on the location). But at some resorts, for example, VWL vs. WL, there aren't as many structural differences other than the sofa bed vs. second regular bed and kitchenette vs. small fridge.
I typically recommend a studio over a regular room if there are two adults who plan to share the bed, or one/two adults for the bed and one/two small children who would share the sofabed. If the children are older, or if you have adults who don't plan to share, then having the second regular bed may be the issue that decides where to book. As a person who travels solo, and loves the microwave and larger fridge of the kitchenette, I tend to book a studio - especially if it's running around the same price as the standard room in the attached resort.