[pbhjpbhj]

I read here previously, I think it was here, that the primary difference was that after repeated counteraction by the crew the speed-trim system would give up, whereas MCAS doubles down and reduces the time between its attempts to force trim "correction", literally wearing pilots down physically until the system wins and the plane crashes.

Another post showed how AoA sensors (IIRC) has systematic errors causing MCAS to operate when corrections weren't required. As you say, lack of redundant sensors.