What is the difference between clinical thermometers and other mercury-in-glass thermometers?

Clinical thermometers.

They can be (and usually made) by glass hollow rods with Mercury inside).

So I would say 'no diiference' considering the fact that: A clinical thermometer made with glass and mercury inside.

Now - a - days other types of thermometers are used (to avoid mercury). Some contains alcohol (for glass type), some are made up like robbons with censors implanted.