Ok , a reground cam like our aftermarket cams,are ground down rewelded all the way around then ground to the new specs. Sometimes you can see the layer on the sides of the lobes.
Cam lobe has a base circle , 2 ramps , 2 flanks and the nose
Base circle the round area where there rocker arms have clearances to the cam,base circle should always remain the same diameter
Ramps are the area that opens & closes the valve,moving the ramps changes when valves open & close,duration
Flanks area between ramps & nose
Nose is what determines amount of lift
Overlap,lobe separation,lobe centers,advance,retard is where it gets very complicated