Master of Arts (MA), Master of Science (MSc)
These Master's degrees are
Master of Arts (MA), Master of Science (MSc), Master of Studies (MSt), Master of Philosophy (MPhil) (Oxbridge), Master of Letters/Literature (MLitt) (Oxbridge)
These Master's degree are equivalent to terminal master degrees of United States universities. It is difficult to distinguish between Low Tier and Intermediate Tier, but most universities will leave hints such as the following example:
"I may want to do a PhD programme in future, which is (sic) MSc is right for me?
If you think that you may want to undertake a related PhD in future then you should apply to the MSc Finance and Economics programme, which is seen as providing world-class training by many leading, related PhD programmes. Please note that our other MSc programmes are not generally regarded as suitable training for most leading, related PhD programmes, including for LSE’s own PhD in Finance."
The MSc Finance for LSE does not prepare for PhD Fiance, but the MSc Fiance and Economics does prepare for PhD Finance because the MSc Finance is a Low Tier Master's degree while the MSc Finance and Economics is an Intermediate Tier Master's degree.
The difference between a Low Tier Master's degree and an Intermediate Tier Master's degree is a Master's thesis.
Master of Arts by Research (MA(Res)), Master of Science by Research (MSc(Res)), Master of Research (MRes), Master by Research (MRes)
These Master's degree are equivalent to Specialized Master, Specialist Degree, and Engineer Degree. They are also equivalent to All But Dissertation (ABD) designation in PhD programs. At times, they are equal to Candidate of Philosophy.
Master of Philosophy (Not Oxbridge), Master of Letters/Literature (Not Oxbridge)
This is the top tier master degree. If by original research, then the dissertation for this degree is said to be equivalent to 2/3 of the dissertation for a PhD as it is a dissertation made of 2 theses in a single topic while a PhD dissertation is made of 3 theses in a single topic.. Typically, this is a separate degree or is a consolation prize for those that will not complete their PhD dissertation. These degrees are 2 year of full time research where the student is unwilling to complete a third year of research to finish their PhD.