I got this same question when I downloaded WSO2 product for the first time. WSO2 Products are licensed with Apache 2.0. So people like me who have similar doubt, please see below for the quick difference. The intention of this note is to give an overview of Apache license 2.0 and just for guidance nothing else.

Apache 2.0 vs GNU GPL?

What is the difference between the Apache License 2.0 and the GNU GPL?
The GNU GPL is a copyleft license. So software that uses any GPL-licensed component has to release its full source code and all rights to modify and distribute the entire code. The Apache License 2.0 doesn’t impose any such terms. You’re not forced to release your modified version. Besides, you can choose to release your modified version under a different license (however, you’re required to retain the Apache License for the unmodified parts of the code).

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