RedHat OpenJDK is described as 'The RedHat build of OpenJDK'. There are five alternatives to RedHat OpenJDK for a variety of platforms, including Linux, Mac, Windows, BSD and Blackberry 10. The best alternative is Java. It's not free, so if you're looking for a free alternative, you could try OpenJDK or AdoptOpenJDK. Other great apps like RedHat OpenJDK are Zulu (Free Personal, Open Source) and Liberica JDK (Free, Open Source).
OpenJDK is the free version of the Java development platform. The OpenJDK project consists of a number of components. Principally these are HotSpot (the virtual machine), the Java Class Library and the javac Java compiler.
The code for Java is open source and available at OpenJDK™. AdoptOpenJDK provides prebuilt OpenJDK binaries from a fully open source set of build scripts and infrastructure. Get Docker Images on Docker Hub. Nightlies can be found in the Archive.
The only certified multi-platform build of OpenJDK : Free, 100% open source Java for Windows, Linux (including Docker), Mac OS X, the Cloud and embedded applications. Featuring tier-one Java support via Zulu Enterprise.