I think we need to refine our terms.
An error is a mistake, either corrected or not. The flipped image 1989 UD Murphy is an error. The 1969 Topps Aurelio Rodriguez 'batboy' card is an uncorrected error. The 1952 Topps Paige-Sain screw up is a corrected error as is the 81 Fleer Craig Nettles.
A variation is a change not made to correct a mistake but to change the card. The Nettles loop is a variation. The Kaline "boo boo" is a variation. The myriad FF Ripkens are variations.
The 1952 DPs are not variations, they are two different cards of each player.
A printing freak is an unintended production process failure. The "Bakep" and "Herrer" cards are print freaks. The 'finger' Fleer cards are freaks. All of the really fun mistakes (IMO) are freaks. They carry premiums because guys like me collect them.
