As a nanny I see my role to be primarily that of caring for the children but it also involves some things to do with the smooth running of the household.
This is not a list of my specific tasks but is what I do...
Changing the children's bedding, making their beds
Washing clothes (children's and adults)
Cooking for the children
Load/Unload the dishwasher
Hang clothes to dry
Fold and put away children's clothes
Sweep the floor / vac the carpets - on occasion, as and when I feel they need doing.
Hunting for lost items - School uniform seems to go walk about easily
Buying occasional things - this week so far: G9 type light bulb (I also fitted it), school water bottle.
Organise emergency sewer clearance/unblocking
So not just childcare but neither is it what I would say would be a housekeeper role.
I feel a housekeeper would do more of things like:
cooking for the household, so including adults
frequent tidying up and vac carpets
wash kitchen floor
clean the bathrooms/toilets
food shopping
Changing/washing parents bedding.
Ironing (if the family do ironing)
Cleaning kitchen and putting everything away neatly.
Dusting
These days I think the role of nanny vs Housekeeper is a bit blurred. Whilst a nanny may focus on children and a housekeeper may focus on housework, both jobs can include things that may be more of the other role.
I agree that the age of the children is a factor... a nanny may well become more of a housekeeper as the children get older, especially once they are all at school.