Orleans vs GPars: What are the differences?

Developers describe Orleans as "An approach to building distributed applications in .NET". Orleans is a framework that provides a straightforward approach to building distributed high-scale computing applications, without the need to learn and apply complex concurrency or other scaling patterns. It was created by Microsoft Research and designed for use in the cloud. On the other hand, GPars is detailed as "An open-source library for high-level concurrency in Groovy". It is an open-source concurrency/parallelism library for Java and Groovy that gives you a number of high-level abstractions to write good logic.

Orleans and GPars can be primarily classified as "Concurrency Frameworks" tools.

Orleans and GPars are both open source tools. Orleans with 5.43K GitHub stars and 1.31K forks on GitHub appears to be more popular than GPars with 209 GitHub stars and 49 GitHub forks.