Many thanks to SlantSixDan for answering my question.
There's nothing significant you'd really need to know. The throttle lever is configured a little differently (the one near the Federated box is a later-production carb with a throttle lever that will work on a variety of '60-'70 cars; the other one will work only on '60-'66 Dart/Valiant/Lancer/Barracuda plus '60-'61 Dodge/Plymouth. There is a minor difference in the choke lever configuration, but it's not important. Yes, the one near the Federated box has a spring-staged choke and the other one doesn't, but they're both for use with the same "well-type" (remote, divorced) choke thermostat.
"Rebuilt" or "Remanufactured" carburetors are usually a losing gamble, but if I had to pick one of these you've pictured, it's obvious more careful attention was paid to the carb near the Federated box, so that's the one I'd try first. The other one has been abrasively cleaned and not recoated against corrosion, which is a sure-fire recipe for severe carb trouble sooner than later once gasoline (which all has alcohol in it nowtimes) begins flowing through it.
