What is motion detection sensor called?

[DNYANDEEP]

I want to add a motion detector to the sealing lights at my home but I am getting confused and don't know what they are called somewhere it seems to be pir sensor and other says microwave sensor . I don't know which one is use for what ur help will be appreciated. I have attached image of something and want to know is this the right thing. I would also appreciate any recommendations u have 

[da na]

PIR  sensors use changes in infrared light to detect motion.

Microwave sensors do the same with electromagnetic waves. 

 

They essentially accomplish the same job in two different ways. 

 

Microwave sensors tend to have higher sensitivity and range but PIR are more accurate.

[manikyath]

PIR basicly responds to variances in infrared light, so if someone enters the room, there will be more infrared light, and the switch responds.

microwave basicly bounces some high frequency signals around the room, and when it deviates from the 'ambient levels' by a certain treshold it activates the switch

 

basicly, one's looking for movement and/or presence, and the other is looking for something vaguely human temperature.