What is the basic difference between Auto Layout and Auto Resizing in iOS

I recommend watching the WWDC 2012 session https://developer.apple.com/videos/wwdc/2012/?id=202

Auto Layout is a new way to define dynamic GUIs. Before, we had autoresizing masks, that described how a subview will resize or move when its superview is resized. With Auto Layout you can do the same and also a lot more complicated GUIs quite easily.

Autoresizing is one of the most useful property for layouting the views in their hierarchies. go through this link.

http://www.techpaa.com/2012/05/understanding-uiview-autoresizing.html

As Matt Neuburg states in his book:

Autoresizing is a matter of conceptually assigning a subview “springs and struts.” A spring can stretch; a strut can’t. Springs and struts can be assigned internally or externally. Thus you can specify (using internal springs and struts) whether and how the view can be resized, and (using external springs and struts) whether and how the view can be repositioned.

And

Autolayout, depends on the constraints of views. A constraint (an instance of NSLayoutConstraint) is much more sophisticated than the "autoresizingMask" it’s a full-fledged object with numeric values, and can describe a relationship between any two views (not just a subview and its superview).