What is the difference between prescription nasal allergy sprays?

I've seen various prescription nasal allergy sprays over the years, such as Flonase, Aquacort, Nasocort, Nasonex, etc. My young daughter was prescribed Nasonex. I had Nasocort at home and asked the doctor if she could use that instead, but he said no, definitely only use Nasonex (which she is). Do all the sprays do the same thing? What's the difference in the relief they give?