The Bolins are interesting examples.
The first one is a printing problem. Overinked, thin ink, or plate too dry or too wet, all have roughly the same result. Unless it's more severe or in a certain spot it's hard to tell.
The ones with the line at the bottom are the sort of thing I collect. While someone else might not call it a variation, it's a difference on the black plate. The line may be either a cutting guideline, in which case there will be another card with the same line at the top, or it might be from the sheet edge and only show on miscut cards. Most of the time, there's another version of the card that even when off center by just as much won't have the line.
I don't chase them all that actively though. And I generally don't pay a premium. Usually the cards are discounted as being poorly centered or otherwise defective
Steve B