The old style of front derailleur has the bar for the cable bolt going horizontal.
The new style has the bar more or less vertical.
The difference is quite recognizable if browsing on E-Bay.
Other differences?
I'm not sure if there is any other difference. I've been using the new style, vertical pull with my 1st generation (white label) SR shifters. It seems to shift fine, although it doesn't seem to take much force to pull the derailleur from the big ring to the small ring, and it will sometimes drop on hill climbs. Perhaps I should try an older generation derailleur to see if it holds the sprockets better.