So is there a difference between EX and normal shield? If it was discussed before, i missed it.
The same thing as in MBAC: EX Shield can be normal cancelled and special cancelled, Shield can only be special cancelled. Auto shield counter/manual shield counter for Full are both considered specials, so those can be done out of Shield. You can only 5D 5A for example if you get an EX Shield. That's why everyone says getting normal Shields in MBAC are suicide, because 5DA is a really common antiair.
Oh, and in MBAA, EX Shields don't weaken your guard bar. Shields do even if you land the shield. Whiff Shields weaken it even more.