skorman hit the big difference, the cowl. You mount the engine inverted in the simply magic but upright in the magic extra. There is also a half inch difference in the wing so the wing loading is slightly different.

Some people don't like an inverted engine so they cut the cowl and mount it upright on the simply magic.

That extra half inch gives the simply magic one more ounce on the wing loading.

I had a magic extra, which is my av pic, I liked it; until I lost it.

If you get one stay within the balance range. Some guys on here say it needs to be further back around 4 inches. If you're not use to flying tail heavy planes you'll lose it on take off. I used a Magnum 46 with hitec 425s and balanced without any added weight.