Hopefully this will solve any problems.
First – Normal 1 1/8" headset – The most common type would fit for example a Cotic soul
Second – This headset fits 1.5" headtubes but 1 1/8" forks – Perhaps more common on downhill bikes such as an Intense M6
Third – Integrated/Campag This does away with cups bearings sit in the frame. I came across this on a BMX frame, but I believe they are popular in road bikes.
Forth – Semi integrated/Internal I think even the word zerostack is sometimes used – This is an arse of a design something like 44mm diameter headtube but fits 1 1/8" forks as used on the Pace RC305
Mog you have the third one just push the bearings in the frame with a bit of grease, fit the crown race to the top of your forks then slot it together.