Although we have stated the goal to have OpenJDK and Oracle JDK binaries be as close to each other as possible there remains, at least for JDK 13, several differences between the two options.
The current differences are:
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Oracle JDK offers “installers” (msi, rpm, deb, etc.) which not only place the JDK binaries in your system but also contain update rules and in some cases handle some common configurations like set common environmental variables (such as, JAVA_HOME in Windows) and establish file associations (such as, use java to launch .jar files). OpenJDK is offered only as compressed archive (tar.gz or .zip).
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javac —release for release values 9 and 10 behave differently. Oracle JDK binaries include APIs that were not added to OpenJDK binaries such as javafx, resource management, and (pre JDK 11 changes) JFR APIs.
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Usage Logging is only available in Oracle JDK.
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Oracle JDK requires that third-party cryptographic providers be signed with a Java Cryptography Extension (JCE) Code Signing Certificate. OpenJDK continues allowing the use of unsigned third-party crypto providers.
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The output of java -version is different. Oracle JDK returns java and includes the Oracle-specific identifier. OpenJDK returns OpenJDK and does not include the Oracle-specific identifier.
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Oracle JDK is released under the OTN License. OpenJDK is released under GPLv2wCP. License files included with each will therefore be different.
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Oracle JDK distributes FreeType under the FreeType license and OpenJDK does so under GPLv2. The contents of \legal\java.desktop\freetype.md is therefore different.
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Oracle JDK has Java cup and steam icons and OpenJDK has Duke icons.
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Oracle JDK source code includes “ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.” Source code distributed with OpenJDK refers to the GPL license terms instead.
https://www.oracle.com/technetwork/java/javase/13-relnote-issues-5460548.html#Diffs
