Yes, 44ID is Zero Stack or semi-integrated. Just like regular headsets they have cups and bearings.
As far as the numbers, the first number is the internal angle of the bearing where the compression ring is and the second is the external angle where it sits in the cup.
36/45 is pretty much standard for zero stack headsets like the Cane Creek and FSA models. 45/45 is the standard for full integrated Campagnolo style headset bearings.