Digital Thermometer:
Clinical thermometers have the practical challenge of disposal of mercury while they are broken down. Mercury is a toxic substance, so it is necessary to dispose of it correctly and safely. To overcome this situation, nowadays, Digital thermometers are used to measure the human body temperature in hospitals.
Digital thermometer
Digital thermometers work on the principle that the electrical resistance of the material changes with temperature. Digital thermometers are different to conventional thermometers, such as liquid-filled and bimetallic thermometers, as they need a sensor. These sensors are producing resistance, current or voltage in reaction to a change in temperature. These changes are referred to as analogue output signals, and they are converted to digital to make them easy to visible.
Infrared thermometer:
Infrared thermometers are typically used to measure the temperatures that are necessary to be measured from a distance.  They give accurate temperatures without ever having to touch the object you are measuring (and even if the object is in motion).
Infrared thermometers