The major difference is oven’s maximum temperature capability.
Standard epoxy connector oven has a maximum temperature of 150 degrees C, and there are different blocks available which will fit each connector style. The oven block feature built in stops to allow the connector to sit in the center of the oven without passing through to the bottom and breaking fiber stubs.
Standard epoxy oven cannot do the Hot Melt connectors.
3M Hot Melt connectors require a temperature of 260 degrees C. Fiber Optics For Sale offers hot melt ovens in 6, 12, and 14 port versions.
Fiber Optics For Sale offers 3M hot melt connector and ovens.
6 port 3M hot melt connector oven
24 port standard epoxy fiber optic connector oven