This is a very disputed subject even for Romanians. Most of us use the form "vroiam" and I am ashamed of the fact that I use it too. I am ashamed because I found out from advised and smart people that the correct form is "voiam" or "vream". There are two verbs: "a voi" and "a vrea" and its each form of imperfect is "eu voiam", "tu voiai"... and "eu vream", "tu vreai". The form "vroiam" is like a hybrid; it's a mix of "vream" and "voiam". The sad thing is that we use "vroiam" very often so that soon, the DOOM will accept it. Some wrong words were used too often as well and got to be accepted as correct ones. It's your choice what you want to use, but for me "vream" sounds more like an old form, used by people from the countryside; this is maybe because I only used the wrong form...

I would say "eu vroiam" and "noi voiam" so the difference is in number - and as a native Romanian, I never heard the term "vream", maybe it's used in the South the full conjugation is: eu vroiam tu vroiai el/ea vroia noi voiam voi voiati ei/ele voiau