I need to explain this to a group of university lecturers and I am not sure how best to describe it.
many thanks in advance for your help
I am not saying that I am an authority, but the best way I can describe it is this:
A rubric is for teacher AND student use, and is mandatory and concrete. For example, a rubric tells you that if you have x number of criteria, you get a A, but if you don't, you get another grade. It is quantitative and inflexible. You either have it or you don't.
A marking guide is more for the use of the teacher who is looking for concepts. But those concepts are not set in stone. An example would be writing a poem. A marking guide would be looking for whether the words rhyme and if they have, say, iambic pantameter. But rhyming is very subjective and is more a part of the cretive process. I don't think there is much room for creativity or personal expression in rubrics, but marking guides are just that - guides!
Does that help?
I'm not sure if Doug realised you mean the advanced grading methods in 2.3
These might help:
http://docs.moodle.org/23/en/Marking_guide
http://docs.moodle.org/23/en/Rubrics
The main difference is that when the teacher is grading, Marking guide lets you enter a number as the grade for a criterion - Rubric has preset levels for each criterion that the teacher can select from when marking that criterion.
Marking guide also lets you build a set of frequently used comments to use when marking.