You know the drill by now, right? Original Marvel comic next to the reprinted version, I look for changes, you spot the ones I miss?
First up, we've got Sgt. Fury #10 and the reprint in Special Marvel Edition #8, and obviously we're looking at an all-new cover here. I'm not sure why, as the original cover would've fit just fine in the new cover dress, except for the top blurbs.
It always amazes me when Marvel would change things on a cover just to change them. Take Sub-Mariner #3 and Tales to Astonish (V2) #3... both figures are reduced, and Namor's been pushed away from the thing (making someone add some toes on Ben's foot), the black background is entirely gone, speed lines are added, and some reinking has been done on Ben, especially on his arms -- or was he entirely redrawn here? Some parts of him look the same, others are different. He's been rotated clockwise slightly, too.
When Amazing Spider-Man #21 was reprinted in Marvel Tales #16, obviously someone felt the original cover wasn't exciting enough... so the moved Spidey over some, got rid of what the Beetle was lurking behind, added another fireball, changed the path of Johnny's flame trail, and altered the fireball that missed Spidey!
Admittedly, Avengers #36 had a rather weak cover... the background machinery was ill-definied at best. When it was reprinted in Marvel Triple Action #28, it looks like some changes were made to bring out the background some more. It appears some of it was reinked as well as recolored, with the background above Goliath changed to some Kirby Krackle, possibly so it wouldn't distract from the MTA logo.
At first glance, the only real differences between Sgt. Fury #26 and #87 are that the scene's been changed to nighttime, but look closer... a downed plane has been added, and the water has been reworked to have more detail. Even the smoke coming off the Nazi ship has been redrawn!
Looking at Tales of Suspense #94 and the reprint in Marvel Double Feature #17, doesn't it look like Cap's head has been redrawn, possibly by Romita? There are subtle changes to the rest of Cap's figure as well, and one of the AIM agents in the background has vanished on the reprint. Modok's gone entirely!
Next, we have Fantastic Four #17 and Marvel Collector's Item Classics #12, and it's an all-new cover. Frankly, Doom does not look right with the mouth of his helmet opened that much! The new cover was apparently a hodge-podge of artwork from different sources, according to the GCD.
Lastly, we have Amazing Spider-Man #108 and the reprint in Marvel Tales #87. Here, we have the background gone entirely... some new smoke has been added as well. I'm not sure why those changes were made, but the whole thing was shifted over for the UPC logo, even though it could've been flipped and still worked. Here, I'll show you, with a quick down-and-dirty version of what I'm talking about: