JDK ist das Developement-Kit, also das was man braucht, wenn man Java-Programme entwickelt (beinhaltet den Compiler). JRE ist nur die Laufzeitumgebung (Java Virtual Machine) und beinhaltet den Compiler nicht.
Oracle Java ist nicht in den Paketquellen enthalten, dafür aber OpenJDK und zwar jeweils als jre und jdk.
Hier mal ein Auszug aus den Paketquellen.
openjdk-11-dbg/focal-updates,focal-security 11.0.8+10-0ubuntu1~20.04 amd64
Java-Laufzeitumgebung basierend auf OpenJDK (Debugsymbole)
openjdk-11-demo/focal-updates,focal-security 11.0.8+10-0ubuntu1~20.04 amd64
Java-Laufzeitumgebung basierend auf OpenJDK (Demos und Beispiele)
openjdk-11-doc/focal-updates,focal-updates,focal-security,focal-security 11.0.8+10-0ubuntu1~20.04 all
Dokumentation für das OpenJDK Development Kit (JDK)
openjdk-11-jdk/focal-updates,focal-security 11.0.8+10-0ubuntu1~20.04 amd64
OpenJDK Development Kit (JDK)
openjdk-11-jdk-headless/focal-updates,focal-security 11.0.8+10-0ubuntu1~20.04 amd64
OpenJDK Development Kit (JDK) (headless)
openjdk-11-jre/focal-updates,focal-security,now 11.0.8+10-0ubuntu1~20.04 amd64 [Installiert,automatisch]
OpenJDK-Java-Laufzeitumgebung, verwendet Hotspot JIT
openjdk-11-jre-dcevm/focal 11.0.3+1-1 amd64
Alternative VM for OpenJDK 11 with enhanced class redefinition
openjdk-11-jre-headless/focal-updates,focal-security,now 11.0.8+10-0ubuntu1~20.04 amd64 [Installiert,automatisch]
OpenJDK-Java-Laufzeitumgebung, verwendet Hotspot JIT (ohne GUI)
openjdk-11-jre-zero/focal-updates,focal-security 11.0.8+10-0ubuntu1~20.04 amd64
Alternative JVM for OpenJDK, using Zero
openjdk-11-source/focal-updates,focal-updates,focal-security,focal-security 11.0.8+10-0ubuntu1~20.04 all
Quelltextdateien des OpenJDK Development Kit (JDK)
openjdk-13-dbg/focal-updates 13.0.3+3-1ubuntu2 amd64
Java runtime based on OpenJDK (debugging symbols)
openjdk-13-demo/focal-updates 13.0.3+3-1ubuntu2 amd64
Java runtime based on OpenJDK (demos and examples)
openjdk-13-doc/focal-updates,focal-updates 13.0.3+3-1ubuntu2 all
OpenJDK Development Kit (JDK) documentation
openjdk-13-jdk/focal-updates 13.0.3+3-1ubuntu2 amd64
OpenJDK Development Kit (JDK)
openjdk-13-jdk-headless/focal-updates 13.0.3+3-1ubuntu2 amd64
OpenJDK Development Kit (JDK) (headless)
openjdk-13-jre/focal-updates 13.0.3+3-1ubuntu2 amd64
OpenJDK Java runtime, using Hotspot JIT
openjdk-13-jre-headless/focal-updates 13.0.3+3-1ubuntu2 amd64
OpenJDK Java runtime, using Hotspot JIT (headless)
openjdk-13-jre-zero/focal-updates 13.0.3+3-1ubuntu2 amd64
Alternative JVM for OpenJDK, using Zero
openjdk-13-source/focal-updates,focal-updates 13.0.3+3-1ubuntu2 all
OpenJDK Development Kit (JDK) source files
openjdk-14-dbg/focal-updates 14.0.1+7-1ubuntu1 amd64
Java runtime based on OpenJDK (debugging symbols)
openjdk-14-demo/focal-updates 14.0.1+7-1ubuntu1 amd64
Java runtime based on OpenJDK (demos and examples)
openjdk-14-doc/focal-updates,focal-updates 14.0.1+7-1ubuntu1 all
OpenJDK Development Kit (JDK) documentation
openjdk-14-jdk/focal-updates 14.0.1+7-1ubuntu1 amd64
OpenJDK Development Kit (JDK)
openjdk-14-jdk-headless/focal-updates 14.0.1+7-1ubuntu1 amd64
OpenJDK Development Kit (JDK) (headless)
openjdk-14-jre/focal-updates 14.0.1+7-1ubuntu1 amd64
OpenJDK Java runtime, using Hotspot JIT
openjdk-14-jre-headless/focal-updates 14.0.1+7-1ubuntu1 amd64
OpenJDK Java runtime, using Hotspot JIT (headless)
openjdk-14-jre-zero/focal-updates 14.0.1+7-1ubuntu1 amd64
Alternative JVM for OpenJDK, using Zero
openjdk-14-source/focal-updates,focal-updates 14.0.1+7-1ubuntu1 all
OpenJDK Development Kit (JDK) source files
openjdk-8-dbg/focal-updates,focal-security 8u265-b01-0ubuntu2~20.04 amd64
Java runtime based on OpenJDK (debugging symbols)
openjdk-8-demo/focal-updates,focal-security 8u265-b01-0ubuntu2~20.04 amd64
Java-Laufzeitumgebung basierend auf OpenJDK (Demos und Beispiele)
openjdk-8-doc/focal-updates,focal-updates,focal-security,focal-security 8u265-b01-0ubuntu2~20.04 all
Dokumentation für das OpenJDK Development Kit (JDK)
openjdk-8-jdk/focal-updates,focal-security 8u265-b01-0ubuntu2~20.04 amd64
OpenJDK Development Kit (JDK)
openjdk-8-jdk-headless/focal-updates,focal-security 8u265-b01-0ubuntu2~20.04 amd64
OpenJDK Development Kit (JDK) (headless)
openjdk-8-jre/focal-updates,focal-security,now 8u265-b01-0ubuntu2~20.04 amd64 [Installiert,automatisch]
OpenJDK-Java-Laufzeitumgebung, verwendet Hotspot JIT
openjdk-8-jre-headless/focal-updates,focal-security,now 8u265-b01-0ubuntu2~20.04 amd64 [Installiert,automatisch]
OpenJDK-Java-Laufzeitumgebung, verwendet Hotspot JIT (ohne GUI)
openjdk-8-jre-zero/focal-updates,focal-security 8u265-b01-0ubuntu2~20.04 amd64
Alternative JVM für OpenJDK, verwendet Zero/Shark
openjdk-8-source/focal-updates,focal-updates,focal-security,focal-security 8u265-b01-0ubuntu2~20.04 all
OpenJDK Development Kit (JDK) source files