I felt the same way when I started looking at BPs! What's the difference between a Normal, Enchi, Pastel, Mojave...? They all looked the same to me, haha.

The localities is a good answer. I'm not super well versed on them, but I have looked at them a bit more recently, especially after finding some really neat ones.

My impression is that it is the pattern and general size differences you will experience. They can be cross bred. Recently a local breeder started introducing some of those lines with Corns. Man, are those hatchlings EVER interesting! Gorgeous little things.

As for exact details and whether or not the seller is being truthful, I'm not 100% on that one. Some locals can look very similar to one another. Such as a lot of the Mountain varities. A lot of the mountain locals have tighter banding than compared to a Nelsons. But, some of these lines of Mountains can have minimalized banding, or increased banding, so they can be tricky to tell.

Hondurans get to be a nice hefty size when they're adults (friend of mine has a beautiful 5ft+ Hypo Honduran. Just gorgeous). Pueblans are a fair size, but not as large as Hondurans. Pueblans typically have a 'flightier' tendancy than some, with a 'Musk now, ask questions later' kind of attitude. Nelsons stay on the smaller end of the scale.

Start to get familiar with the bands, and head markings. Those will give you some clues. Nelsons have large red bands and their black and white/yellow bands are typically tighter together. Hondurans have thicker markings, with a smaller red area than Nelsons, and wider black/white/yellow markings. Most Pueblans I've seen have a lighter band on their head, similar to the Nelson but with wider bands. They strike me as very beautiful snakes, as their banding is typically very thick.

Unfortunately, I wish there was a bit easier-to-find information about these animals online. All I've gathered here are bits and pieces from other forums, so please do NOT quote me on this, haha.

But overall, Hondurans seem to have a pretty good reputation. Pueblans are nice but a bit musky and sometimes will resort to pooping on you. Nelsons appear to be calmer, but are on the smaller side.