IAME vs. Yamaha.
Reed valve vs. piston port.
Electric on-board starter vs. external starter.
Low maintenance/low stall clutch vs. high maintenance/high stall clutch.
Tillotson vs. Walbro carb.
KA100 has a few more hp.
KA100 seems to need less blueprinting & rebuilds.
KA100 is pipe exhaust, you can put a pipe on the KT100 but the “can” exhaust is more popular especially in sprint racing.