In some countries MCS (2 years) is offered as a 16-years graduation degree, which is equivalent to BS(CS). It is offered specifically for those who have earned a 14-years bachelor degree or sometimes for people coming from other backgrounds, to provide them a fair enough base in computer science.
A computer science MS or MSCS are both similar terms (2 years long), which is an 18-years graduation degree.
Coming to your question:
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?
The answer is: Yes, MCS is like any other professional degree out there. In addition, after having an MCS degree, an MS degree (2 years) is still pursued to get prepared for a PhD degree.
MS degree mostly has a thesis, while MCS, if it has the one that is definitely, we can say the lighter one, since the candidate has not been trained at this level to produce a thesis.
Does the thesis help you getting hired?
This simple most answer is: "It totally depends upon the employer and her demands for a specific position offered".
As I said:"MS degree mostly has a thesis". Well I know people and the universities were they have MS degrees (18 years) but without a thesis. So how do they do this? Mostly they compensate the research credits with additional course work.
I also know places/individuals (internationally) where people with 'MS degrees without a thesis' have also been haired for an explicit research positions (e.g., Research associates, PhD students with RA ships, etc.) in academic institutes for academic research. Where, mostly thesis is a requirement OR in other words a thesis is inevitable to provide a candidate with the required skill set for such positions.
Finally, while considering the above description about the acronyms valid, I would say that a thesis with an MCS degree has an importance similar to to any other professional degree with thesis (i.e., the case when a thesis is also prepared at end of a professional degree in order to fulfill the requirements).
N.B. Some universities also name MCS to a computer science MS degree.