A Full Stack developer works with both the front and back ends of an application. They can handle projects that involve databases, building user-facing websites, and also work with clients during the planning phase of projects.
A MEAN stack developer works with some particular areas alone. They refer to the development process that comes under these particular set of technologies MongoDB, Expressjs, AngularJs, NodeJS. In short, MEAN stack developers are like JavaScript-based application developers.
If you are looking for online courses to learn full stack and mean-stack development, check out this Full stack Developer Course by Intellipaat.