A glacier is a huge, slow-moving mass of ice formed from compacted snow, and it stays on land, creeping down a valley or mountainside over years. An iceberg is a chunk of ice that has broken away from a glacier or ice shelf and now floats freely in the ocean. A simple way to remember it: a glacier is where the ice is made and lives, an iceberg is a piece that has left home and gone to sea.
The core difference
A glacier is a land-based mass of ice that moves slowly; an iceberg is a broken-off piece of ice floating in open water.
- glacier — a large, slow-moving mass of ice formed from compacted snow: The glacier has retreated significantly over the past century.
- iceberg — a huge chunk of ice that has broken off a glacier or ice shelf and floats in the ocean: The ship altered course to avoid a massive iceberg.
- iceberg — figuratively, a person who seems cold or emotionally unreachable: He acted like an iceberg during the whole meeting, giving nothing away.
How to tell them apart
The relationship between the two words is almost like parent and offspring: a glacier calves an iceberg when a piece of its ice breaks away and drifts off into the sea. If the ice is still attached to land and creeping along under its own weight, it is a glacier; once it has separated and is floating, it becomes an iceberg.
Iceberg also carries a figurative sense that glacier does not, describing a person who seems cold and gives nothing away emotionally. Only a small part of an iceberg shows above the water, which is exactly why the saying about the tip of the iceberg is used for a problem that looks small but is mostly hidden.
