Sun made a mess of the
Java versioning scheme.
First there was Java 1.0 and 1.1. Then came Java 1.2, which was also known as "Java 2 SE" (J2SE) and then J2SE v1.3 and 1.4. And then they decided to rename it to "Java SE 5" v1.5, etc. There were supposed to be two version numbers, the marketing version number (5.0, 6.0, 7.0, 8.0) and the internal, developer version number (1.5, 1.6, 1.7, 1.8). Totally unnecessary confusion...
Likewise with Java EE, which became J2EE and later went back to Java EE.