While it presents a rather inconsistent product by having different service flows/setups between pmUA and pmCO aircraft, the food is the same and this is the best breakdown I can give:

pmCO:
-drink orders handrun from galley
-tray setup from 3-tier cart/meal handrun from galley
-cold appetizer not pre-plated (it used to be multiple selections on pmCO until recentl) served from 3-tier cart
-salad served seperate handrun (i think its a larger portion)
-Cheese course served from 3-tier cart (may have changed but used to have more selections)
-cappucino/espresso machines on 767/777

pmUA
-drink orders from beverage cart
-tray/meal setup from cart (bulky cart not 3-tier)
-cold appetizer pre-plated served from cart (you get what you get)
-salad pre-plated (seemed to be smaller portion) served from cart
-Cheese pre-plated (may have changed but I thought this was how they were serving it)
**there are some elements that use a 3-tier cart, but the main difference is use of the larger cart and pre-plated items

The differences now are minimal. In the beginning, BusinessFirst on pmCO was superior to the experience to on pmUA....but they figured by cutting the extras from pmCO aircraft they could align with pmUA. Now they both are mediocre