Correct. One is measured @ .050" lift and the other @ .006".
A careful look at the Whiplash/Thumper type cams listed on the previous page shows that the Thumper cam will close the intake valve sooner @ .050" lift than the Whiplash cam. An earlier suggestion, of the 21-222-4 cam, will close the intake at 31 ABDC @ .050", which is sooner that both the others, and can potentially give an even greater increase of cylinder pressure.