vim omnicomplete vs. vim intellisense

Vim Omnicomplete is a feature of Vim version 7, on all platforms. Vim Intellisense is a plugin for vim 6.1 and 6.2 on Windows only.

OmniComplete and Intellisense are different words for the same thing, a kind of autocompletion system.

Intellisence is a trademark of Microsoft. So the author of vim (Bram Moolenaar) decided to give this feature a new name, OmniComplete.

If you want to have autocompletion for C++ you have either to activate/configure the build-in OmniCompletion or you have to install the plug-in Vim C++ Intellisense.