Why there is a MX library and also a Spark library in flex? [duplicate]

Question

This question already has answers here:

ActionScript MXML <mx:> vs <s:> (3 answers)

Closed 6 years ago.

I'm new to flex, and very confused with that there is a "MX" library and also a "Spark" library? They have a lot of similar controls.

Why both of them exist? Which one should I choose?

Answer 1

MX is the old Flex 3 Library.

Spark is the new Flex 4 Library. It has way better skinning/styling Capabilities, is faster and optimized for mobile.

IMHO in 95% of the cases Spark is the better choice.

Answer 2

New flex architecture is spark. Spark components are skinanble and more lite weight. Also spark components could be used at mobile applications.

So if possible use spark components.