What is the difference between a Dura-Ace FD-7803 Tripple 34.9mm clamp Front Dérailleur and an XTR 34.9 bottom pull dérailleur?

Functionally are the exact same?

Correct me if I'm wrong, but in general mountain bike chainlines are 50mm and roadbike chainlines are 43.5mm right? Is this the difference between Dura-Ace and XTR in the above question?

What is the difference between a Dura-Ace FD-7803 Tripple 34.9mm clamp Front Dérailleur and an XTR 34.9 bottom pull dérailleur?

Functionally are the exact same?

Correct me if I'm wrong, but in general mountain bike chainlines are 50mm and roadbike chainlines are 43.5mm right? Is this the difference between Dura-Ace and XTR in the above question?
I believe that there is actually a slightly different amount of cable pull for the front on road vs. MTB shifters.

Another view: I don't remember where and it's been a year or two, but I read someplace about a bike company that was making a CX bike and using a pulley so that they could use a BP (road) FD and still have the cables running along the top tube. They said that they did this because the only TP FD that shifted 'acceptably' was an XTR and the these were too expensive to spec on their bikes. ????

TF

I believe that there is actually a slightly different amount of cable pull for the front on road vs. MTB shifters.

TF
That's correct. For some reason if someone **must** use a Shimano mtb fd with a Shimano road STI lever, you can usually get it work fairly well by clamping the cable on the underside of the clamping bolt as opposed to the top side.

Another difference between the mtb and DA triple is the cage itself. Both are profiled
/designed for a much different chainring combo.

The XTR is made for a 50mm chainline and the DA would be made for a 45mm triple chainline. The XTR is made to properly shift a 44/32/22 setup, not a 53/39/30.

While a road double chainline is specified as 43.5mm, the reference point is entirely different - to the midpoint between the two rings. This is worthless information to the average user, since you can't spot a point in midair. What needs to be specified is the position of the big or little ring. With typical 7.5mm spacing, the tip of a tooth on the big ring will be in the 47-48mm range. A road triple will be 5-6mm further to the right.