Does one or the other include wheelsets and/or shifters, etc.?

They are the component levels. Dura Ace is the highest quality, the lightest and the most expensive level of Shimano components for road bikes. Ultegra is the next level down from Dura Ace.

either one is a name for a complete set of 'everything but the frame & tires' on a bike

either one is fine

they r both made by shimano

dura ace is much more expensive, a little lighter [not necessarily stronger or more durable though], somewhat flashier looking

obviously there can be any mix of components

actually it;s pretty rare for a bike to be all dura-ace or all ultegra

even all-shimano is getting to be an oddity

and there r competing brands
campagnolo
sram

a 'dura ace' bike will cost u 1600-2000 & up
the same bike with ultegra components might be 1000-1500
shimano;s other traditionally named lines are
105
tiagra
sora
in descending order of expense & perceived quality
at least in road bikes

to me, dura ace is beyond the point of diminishing returns
ultegra is perfectly fine for the cost reduction


wle.

Here is the Shimano web site, mouse over the products then over road bikes. The highest quality is at the top, u can click on the group set u want to look at. Most of the time it will be the shifters, brake levers & the front & rear derailleurs in that group. Usually there will be a different wheel set & brake calipers. You can buy packages that contain the whole group set. You have to look at the manufacturers spec is to see what is actually on the bike.

http://bike.shimano.com/