On a camshaft the lobe seperation angle is ground into the camshaft by the grider, and is the relation of the lobes to themselves. the instaled centerline is the relationship of the number on intake lobe centerline to the number 1 cylinder at tdc if this number matches the lobe seperation angle the cam is instaled straight up, if these numbers do not match the difference is expressed as advanced or retarded. I believe that the lobe seperation angle is expressed in camshaft degrees and the installed centerline is in crankshaft degrees, but my brain is tired so you should check it out yourself. lobe seperation angle is generaly a larger number on stock or low performance engines and smaller on race type engines. in my experence most off the shelf full race grinds have a lobe seperation angle of 106 while many street grinds have a lobe seperation angle of 112 to 114. lobe seperation angle affects overlap, this affects cylinder pressure at low rpm, a low compresion street engine will work better with a larger lobe seperation angle.
I hope this helps a little