What’s the difference between an optician and an optometrist?

When you come in for your eye test and any subsequent examination, you will probably meet and be looked at by several different individuals. Different eye care specialists carry out different roles, so what’s the difference between an optician and an optometrist?

A blonde-haired woman having her eyes testing using equipment operated by a bespectacled and bearded optometrist.
A blonde-haired woman having her eyes tested by a bespectacled and bearded optometrist.
Extreme close-up of eye with green iris and black pupil.
Man with short hair and blue shirt having his eyes tested by a dark-haired woman looking into testing equipment.
A man with dark hair and a dark blue shirt sits trying on a pair of prescription glasses while a woman in a white blouse stands behind him.