Arial Vs Arial MT

Hello,

Is there a difference between Arial and Arial MT fonts? I have Arial TTF in my windows fonts directory. I searched and there are few bits and pieces that allude to both of them being "essentially the same" but nothing conclusive. I also thought Arial was a Base 14 font and so will not get embedded in a pdf document. But, I have a pdf from a third party source where Arial MT is embedded.

Anyway, my problem is that I use a third party report generation tool (Report Mill) to create a pdf. The font that I am using is Arial but on the fonts panel in the generated pdf, it is listed as Arial MT, not embedded and gets displayed as Helvetica. Helvetica is better in my opinion, but that is not what is wanted by others.

I am also trying to talk to the third party vendor, but any input of Arial Vs Arial MT and why I Arial font is embedded in pdf when it is a Base font would be very helpful.

Thanks.