Boats are generally smaller than ships, and not designed to cross the high seas and oceans. The exceptions are lifeboats and fishing boats and some ocean-going yachts.

Perhaps the most famous use of a boat was by Grace Darling. She and her father had nothing but a large rowing boat, yet they set off from their lighthouse to rescue sailors in distress whose ship had struck rocks in a storm.

The video shows a modern lifeboat used for emergencies by a ship, so you can get an idea of the difference between a ship and a boat.