Need 2D animation advise, Spine v.s. SpriteStudio?

I am kind of confusing here, what’s the main difference for following two tools for 2D animations:

(1) Spine: http://esotericsoftware.com/

(2) SpriteStudio: http://www.webtech.co.jp/eng/spritestudio/index.html

Anyone can shed some light or share the experience with them? or any advises about 2D animation?