In my experience the ornamentals have less fruit, but it's still edible. Here's a more thorough explanation of the difference:

http://homeguides.sfgate.com/difference-between-quince-ornamental-quince-fruit-65846.html

Flavor of ornamental fruit may be more concentrated; they are typically used as a flavoring or gelling agent, rather than tree quince that can be treated like apples if baked, cooked, or juiced.

Membrillo, a common quice dessert, is usually made from tree quince.

Answered on your duplicate thread on the Shrubs Forum.

Some fruit more heavily than others. My grandmother had a very productive strain of C.japonica. I used to eat those exquisitely sour fruits when I was a kid. Have seen claims that you could substitute Chaenomeles fruit for Cydonia in any quince marmalade recipe.

Think I have cored and cooked them, similarly to Cydonia quince fruits, and they're good...albeit a lot smaller.