Camshafts

[midgetracer]

I have four 5 bearing camshafts. one has the second and fourth bearing with oil grooves. the grooves are wider and deeper than three bearing camshafts. The 2nd and 5th bearings are the same size (1.558in) as the other 3 bearings.
The other three have no oil grooves on the 2nd and 5th bearings and they are smaller (1.44 inches dia) than the other 3 bearings. Any idea why they are smaller and what the difference between the cams mean.