Difference between GlassFish Server Open Source Edition and Java EE 6 SDK Update 2?

Can anyone tell me the differe开发者_运维知识库nce between GlassFish Server Open Source Edition and Java EE 6 SDK Update 2? As far as I know the GlassFish Server Open Source Edition 3.1 is included in the Java EE 6 SDK Update 2. But what else? Couldnt find any information.

On the Java EE 6 SDK Downloads page, I found the following:

Java EE 6 SDK Update 2 includes:

• GlassFish Open Source Edition 3.1

• Java EE 6 Code Samples

• Java EE 6 API Documentation

• Java EE 6 Tutorial

• Your First Cup: An Introduction to
  the Java EE Platform