Originally Posted by urodacus

integrated headset means that the cups for the headset are part of the frame...

supposedly lighter, but probably used to make manufauring cheaper. not able to be replaced, so if the bearings die, so does the frame.
Now, the rival system of an "internal headset" is a different matter: the cups from a headset like an Orbit (vane creek) are pushed into a recess inside the frame, and thus the whole bearing set is hidden from view which is supposedly better for wind resistance(?) and gives a wider headtube (which defeats the wind resistance idea) but gives you a stiffer fork mounting.

make sure you're not confusing integrated and internal systems.