MyEclipse is a set of integrated plugins to the eclipse platform, built on the eclipse classic distribution which includes basic java development tools.
It is packaged in various ways for flexible installation. It may be installed as a feature set for eclipse or as a standalone installable IDE that includes eclipse and a JDK in the same package. It may also be installed via an external installer, Pulse.
MyEclipse comes in various editions that package together integrated tools for particular development situations.
Please refer to the download page for the particular edition that you are interested in for the different all-in-one installers or for the method of installing into eclipse classic. Alternatively, go to the Pulse website to download the free pulse installer to manage multiple installations of the IDE.