There are basically no difference in funcionality, only in RDP you dont have admin rights so you need to ask the server admin if you want to install certain apps, though... most of the RDP sellers already place some essential apps in there; as for VPS... you have the admin rights so you can install whatever apps you want... but there's no single apps installed when you got it so there will be some hassle on the first use.

I recommend RDP if you want to seed, download, and upload.