In general: females are more organised, better at paying attention, and able to work better than males - and so it gives them a greater advantage with these skills to be able to take time to write notes, organise them well (some girls i know are ridiculous with their organisation its actually painful) and then memorise it.
for some, having well organised notes, that are full of different colours and neater can make it easier to memorise, not only is writing it going to take longer, so the information is in mind for longer but the colours/fonting can give different cues and such for easier recall.
remember this is just the generalised norm that occurs, and in no way truly representative of everyone..
(though it is definitely true for my experiences... ha)