What sensor do high-end rice cookers have that varies the cooking dependent on the rice variety? Steam?

Simple rice cookers have only a 100°C temperature sensor (or switch) that turns off the main element once the water is boiled.

Some rice absorb water very quickly, some rice very slowly, some rice you want more water, some very little, sometimes you want to add other ingredients too. That's more than enough to vary cooking times but not be able to estimate cooking times via the sensor.

Obviously.

My question is what sensor do they use to detect the difference?

I did some Googling but couldn't find any info.

IIRC, it's just temperature (and maybe time). Once the bottom of the pot goes above boiling, all the water has been absorbed/boiled off. Cheap rice cookers then just click over to warm, fancy ones might do something based on time, which can change based on other things like how log it took to come to a boil or how long between coming to a boil and the water finishing absorbing.

Usually the cooker senses the temperature and amount of unabsorbed water left (conductivity ? ai forgot the exact input but Technology Connections had an excelent video on youtube on rice cookers for those interested).

That's enough to manage a temperature curve and predict the last 10~15min of cooking (mine shows a time only 15min before the end), and doesn't require much input from the user.