How many types of iot level sensors are there?

More and more iot level sensors are being used to measure the level of various medium. To be honest, I don't know what it's actually used for or how to choose a model. More importantly, what are its advantages over ordinary level sensors?

Hope you can answer.

Thank you!

In terms of measurement, the iot sensor is no different from an ordinary level sensor. The basic feature of the IOT sensor is that it is easy to transfer the measured data to software systems.
The most important issue in measuring devices is the condition of the measuring device being supplied with battery or external energy. According to this situation, the communication protocol of the device may change.
Prior to IoT (M2M in the foreground), there was no standard in communication protocols. Each sector was communicating through its own communication protocol.
With IOT, these protocols began to standardize.
The most commonly heard protocol, MQTT, becomes a common protocol for all sectors.
NB-IOT is the solution for battery-powered systems.