M. exuberans is a late summer burn morel that is large and robust, and has a tinge of green to the flesh. These are the "greenies" or "pickles" of the mushroom industry. M. brunnea is a very plain small brown morel that is also a pine associate, though it is NOT a burn morel. It is often referred to as a "brush morel" or just a "pine morel".
These are very different morels that should not be confused with one another.