I think you're confusing technologies here.
NVIDIA Optimus is the codename for the dual graphics card split enjoyed by a wide variety of "gaming" laptops with "dedicated" graphics. It has nothing to do with any form of software, it's merely a type of hardware setup.
Thereby, NVIDIA Prime is NVIDIA's solution to implementing Optimus usability on Linux. That being said, NVIDIA Prime is closed-source. It also has an annoying tendency to drain laptop batteries, as the discrete card usually stays enabled due to the lack of per-application switching found on Windows.
The open-source software community attempted to fix this with the creation of the Bumblebee project. Instead of using the always-on or always-off mode of Prime, Bumblebee created a utility called
optirun that allows you to specify whether a program should be loaded with the discrete graphics card or not. However, reports of Bumblebee's performance are mixed at best, and have been known to be relatively buggy.
It would ideally be better to try Prime and Bumblebee (you can switch between them rather easily) and just decide which you like more (which gives you better performance, a longer battery life, etc.).