I think the first Washington 3c green shown here was issued either by the Continental Bank Note Company in 1873 or the American Bank Note Company in 1879. However, since I’m not a student of these issues, I can’t be sure which one it is.
From what I’ve read, even experts don’t always agree on which company printed a given stamp, so I don’t feel too bad about not being able to tell the difference myself.
The 2nd stamp is a re-engraved version of the 1873 (or 1879) type. What were originally vertical lines are now so thick that the area appears to be a solid color and more shading was added to the arabesques in the upper corners. The problem is that you don’t really notice this at first glance, so that’s why I consider them the same catalog number.