A boarder is a person, for example a pupil who lives at school or someone who rents a room, while a border is a line or edge, such as the one between two countries. Memory hook: a boarder is the one who does the boarding, so it ends in -er like a person word.
The core difference
A boarder is a person who boards; a border is a boundary or edge.
- boarder — a person who lives in lodgings or at a school: She was a boarder at a school in Kent.
- border — a dividing line or an edge: They crossed the border into Canada just before sunset.
- border as a verb — to lie next to: France borders Spain to the south.
How to tell them apart
If you mean a person, use boarder. A boarder is a pupil who lives at school during term, or someone who pays for meals and lodging in a house. It comes from the verb board, and the -er ending marks the person doing it.
If you mean a line, an edge or a decorative strip, use border. The mix-up shows up in writing about travel and immigration, where boarder sometimes appears by mistake for the line between two countries. It is border every time: border control, border town, a lace border on a tablecloth.
