Let's see. Horse 1 had a nice slope to his shoulder, and overall is nicely balanced with good muscle tone. He has a nice long neck, but his throat latch is a little on the thick side. He does have a few structural problems, aside from being built down hill (which he'll mostly likely grow out of considering he's two). As waresbear pointed out he is sickle hocked, which really isn't uncommon in the stock horse breeds (I'm assuming these are paint/quarter horses) and can actually be desirable to an extent for certain disciplines such as reining. He's also over at the knee and toes out in the back.
Horse 2 has a slightly steeper shoulder than horse 1 which will probably cause him to have a little bit rougher stride but nothing too extreme (we're talking maybe 5 degrees difference). Colt 2 is also pretty well balanced although he has a little less substance to his hind quarters. Though, that could very well be because he's younger; he'll probably fill out more as he gets older. His neck ties into his shoulder lower than horse 1, but this isn't necessarily a bad thing especially if you plan on using him as western pleasure horse as he'll be naturally inclined to carry himself with a nice level topline! Your colt definitely has horse 1 beat structurally speaking. He is also built slightly down hill, but to much less extent than horse one. With him being younger he should level out just fine which will make him lighter on the front end and therefore more maneuverable when you start riding him. He is also a teeny bit over at the knee, but again not nearly as noticeably as the first horse. It's kind of hard to tell what his back legs look like from these pictures. He looks almost post legged in the bottom one but I'm guessing that's just a combination of the angle and the way he's standing.
All in all I think you made a good choice. I think your colt will be easier to keep sound and he's pretty colors to boot! What are your plans for him?