Integrated uses bearings that are pressed directly into the headtube. No cups in an integrated headset. Internal is the same as a regular headset except in the larger size. Internal still uses cups that press into the headtube and bearings that seat into the cup.
FMF Pro 2 tube Carbon BMX and Gary Fisher Hoo Koo E Koo
Internal Headsets sit inside the frame so you dont see much of the headset, it is lighter then an intergrated headset, a Chris King is an intergrated Headset, my bicycle uses a Internal headset, you press the cups in and then the bearings sit inside those cups, so it makes a cleaner look. generally Intergrated are more popular.