Birth is what happens when a baby or animal is born, or the start of something new. Berth is a completely different word: a space where a ship docks, a sleeping bunk on a ship or train, or a secured spot such as a place in a tournament. A quick memory hook: berth has an "er" like harbour, since both relate to docking.
The core difference
Berth is about ships, bunks, and secured spots, while birth is about being born or something starting.
- berth — a space where a ship docks, or a sleeping bunk: the ferry pulled slowly into its berth at the harbour.
- birth — the event of being born, or the start of something: she was exhausted but overjoyed after the birth of her son.
How to tell them apart
Because berth and birth are pronounced exactly the same, spelling is the only thing that separates them. Linking berth to harbour by the shared "er" is a reliable trick, since both words concern a ship finding its spot to dock.
The confusion tends to surface in travel writing, where someone books a berth on an overnight train or ferry and a spellchecker, or a tired writer, slips in birth instead. It also appears in the phrase "a berth in the finals", meaning a secured place, which has nothing to do with being born.
