Quoted from wiki, not the best source but seems to agree with what I thought and what most people here think:
BSc - Bachelor of Science
MSci - Master in Science (Master of Natural Science at Cambridge University)
MSci - Integrated Master in Science
BMSc - Bachelor of Medical Science
This may be what you were thinking of
In general any masters is at least 1 extra year, it is a higher qualification.
Also I know for a fact that honours is what you get if you pass all your modules first time above the given rate (usually 40%), depending on the Uni you are allowed to fail so many modules and still pass the degree but you then get it without honours.
Within the honours degree you get graded 1st, 2.1, 2.2, 2.3, 3rd depending on how well you do % wise.
Different Uni's have different rules regarding how many resits (sometimes 0) and how many modules you can fail, and at what % the pass rate is set so getting honours is harder/easier depending where you study.
(At the 2 Unis I attended it will be based on the credit system, with modules being worth 5-40 credits and you can fail 10 credits of final year, some modules you must -not- fail though)
Also worth knowing, if you do the MSc all in one go, as in apply for it through UCAS as a part of the undergraduate BSc, then it will have the possiblity to have hons.
Masters done after you already graduated from the BSc as a separate or additional year/course are a postgraduate masters and not the sort that get hons
Doesn't make either better or worse, the way I see it is the hons part of it refers to the BSc part.