I hate to man the post, but whats the difference between a incubator and a hatcher?
For incubating, eggs need to be kept warm, at the right humidity, and turned regularly.
For hatching, the eggs still need to be warm and at the right humidity, but they should not be turned. As the chicks hatch, they move around and make a mess of sticky stuff and eggshells and bits of down.
Some people put eggs in their incubator every week, and every week they move the ready-to-hatch eggs to a separate hatcher (which might just be a different incubator.) That keeps all the mess in one place, and keeps the chicks from jostling the other eggs as they move around after hatching.
For large cabinet-style incubators, the trays often tilt to turn the eggs. The hatcher versions have trays that do not tilt, and often have covers for the trays so chicks cannot jump out. That could be very handy if someone was hatching different breeds and did not want the chicks mixed up.
For commercial hatcheries, they deal with so many eggs that having separate incubators and hatchers makes lots of sense. They hatch so many eggs every week that it's worth having a special machine for each part of the process.