The inside of one lamp might be coated white while the other might be a reflective metal finish. Not sure though. You would have to verify in person. I think I've read that the white finish is better for a basking light. The reflective finish can kick out too much heat and fry your animal.
I had a mini deep dome (white finish) for my guy. Works well if space is limited, but I recommend a wider fixture if you can. Provides a larger heat gradient which is ideal.