I think you have to look at the individual nursery/pre-school on a case by case basis to work that out.
My DS goes to a pre-school which definitely offers much more than the nurseries I looked. The latter were more about daycare than education iysim. His preschool has a better staff-ratio and (imo) ethos and a lot fewer children. But I am sure that there are some nurseries out there which are just as good and yours may well be one of them.
I will be interested in the replies; my DS is not at nursery yet but I understood preschool to be for SAHM/CM as they have fixed sessions, e.g. 9.30-12pm which is unlikely to fit in around work, and therefore are more for socialising the children and preparing them for school. Whereas nursery is more for actual required childcare for working parents, and is much more expensive. But I will be working 3 days a week and would consider putting DS in preschool on my free days when he is older maybe for 1 morning a week so I can get a bit of time to myself. Also I'm not sure if a local preschool feeds into my preferred primary and whether it gives any advantage when applying. Can you do both nursery and preschool?