M.S. or PhD in Engineering - what's the difference in the U.S

[atay5510]

I am a final year undergraduate student from Sydney, Australia an am considering applying to grad positions in the U.S, in 2013. I will receive a Bachelor of Engineering (Biomedical Engineering)(Hons) and a Bachelor of Science (Physics) at the end of the year from arguably the best university in the country. Our system works differently to yours in that we have to stipulate what field we want to study at the beginning of our college careers.

My question is, if I wish to do a PhD in Bioengineering, in my graduate school admissions, should I be applying for a PhD in Bioengineering or a M.S. in Bioengineering an apply to upgrade from M.S. to PhD at the end of my first year? Is that even possible (that's usually how it's done in Australian universities).

The fact that I have (Hons) after my engineering degree means I have completed a year-long undergraduate research project in my engineering field of expertise. I believe this is somewhat similar to a M.S. but there are definately diferences

In any case, I would really appreciate any advice I can get

Thanks