I have just graduated with a 2.1 from my first degree in Biology and am looking to apply for Masters starting next summer.
I know what the shortforms of qualifications literary stand for but am still confused about details.
Having read a range of threads on this page, MPhil seems to be a "pseudo-qualification" to keep official PhD dropout rates low, right? However, what is the difference between MRes and MSci qualifications/courses?

An MPhil is a valid qualification but can also be used in the cynical way in which you (and me in previous threads) describe. The difference between an MPhil and a PhD is firstly an MPhil is shorter and secondly the research carried out during and MPhil, whilst needing to be worthwhile does not need to be new (i.e. you can repeat the research/experiments of others and draw your own conclusions).

An MRes is a training in research methods and is best chosen if you think you may want a career in research. Remember however, that the names of these degrees is up to the universities themselves, and does not indicate what criteria the course fulfils. Before the MRes was invented 10 or more years ago very similar courses existed, but were just called MSc's. Some MSc's around now will cover much the same ground as an MRes. In other words, don't worry about the name - look at the content of the course to make your decision.

Im doing a MRes myself and the only difference is that we have more time for the research project and less modules. This is the better choice if you want to enroll in a PhD.