What is the difference between a twitch and a tremor?

Twitch/Tremor: twitching is of short duration and usually occurs once such a muscle jerk. tremors are usually repetitive and cyclic.

Size of action: A twitch is a small action, of the face, eye, shoulder, hand. A tremor can involve the head, the body, both hands. Both can be repetitive. A twitch typically doesn't interfere with function such as handwriting or activities. A tremor usually disappears during sleep or when the limb is supported or held still. A twitch can persist even when the person is sleeping.

Twitch v tremor: A twitch is normally a single movement, sometimes involving part of a muscle. It may be a local event, not related to the brain. A tremor is a repetitive, often continuous movement, typically involving multiple muscles, and it is driven by subconscious commands from the brain.