Difference between computer science MS and MCS I'm planning to apply for a master in computer science, and I need to choose between a computer science MS - master of science, and a computer science MCS - master of computer science.
I haven't really understood the difference. Is is true that MCS is more "professional" in the sense that it doesn't prepare students for a PhD but it is for who wants to directly work after graduating? Do they both last 2 years?

EDIT: I've also found MSCS: master of science in computer science.

PS: So for example MSCS has the thesis. Does the thesis help you getting hired?
Many Master's degrees exist that could reasonably be considered "computer science" degrees, and the distinctions between them differ from one university to another.  Thus, you should probably ask someone familiar with the programs that you're considering about the particulars for that scenario.

The best general answer to your question, if there is a general answer to it, is that many of the degrees named simply "Master of Science" require writing a thesis.  For example, compare North Carolina State's Master of Science program with their Master of Computer Science program.  Often the thesis degree is awarded to PhD students who have completed their qualifying exam and coursework, but this also varies from one university to another.

Since writing a thesis is an important distinction for Master's degrees, you may wonder what a thesis is and how it might be viewed by potential employers.  A thesis is a document produced as the result of academic research.  While you will learn more about analyzing academic research, formal writing, and how academia works in your field of study, you will not typically learn more skills that are directly applicable to the profession.  For this reason, you can think of the thesis master's as an "academic" degree and the non-thesis master's as a terminal "professional" degree, but that's also a bit of a simplification. 

If you're looking at degrees that start with "Master of Science in" and end with something like "Computer Science," "Computer Networking," or "Software Engineering," then you probably won't have to write a thesis.  These Master of Science names differentiate a degree in science, engineering, or medicine from a degree in English, history, or philosophy, which are Master of Arts degrees.  Often, these are both shortened to just "Master's" degrees.  So instead of a Master of Arts in History, you might simply say that you have a Master's in History.  For example, NCSU has a Master of Science in Computer Networking, which is regularly shortened to Master's in Computer Networking.