"The people living upstairs" is more natural.

Kira, both are correct. I would say "the people living upstairs." However, if there are more floors above you than just one, saying "the people on the floor above me..." would clarify what you mean.

The people living upstairs, I though

both r okay,but i will make some corrections tho it would be better if you rephrase it like "people whose living on the floor above" hope it helps

to me those both all the same mean. and because the word "upstairs" has already meant" on the floor above"', people tent to you "upstairs" for a shorter sentence. beside the second stence you should write "people living on the floor above were noisy" it sounds longer right? even though english learner like me don't bother about that xD