Shining also has had, what I guess to be, high level military training. Being captain of the guard and all. While Twilight, on the other hand, still has untapped potential power. Also, if magic is like any other skill, and Shining only trained in or practiced the most at making force fields and related defensive/offensive magic. This would explain why he was able to make a massive forcefield. If Twilight is given more time and the same training her power could be much more than it is now.