Traditionally in the UK, brake horsepower (BHP) is used to measure a car’s power. Horsepower doesn’t take into account the frictional losses in power from an engine, whereas brake horsepower does.
This means HP is always higher than BHP. The difference between the two is small on a 1:1 basis, but when you scale it up, they become more pronounced.
A car with 300hp, for example, would have 296bhp. Power figures are typically published in the HP format, but a lot of traditional car magazines still convert to BHP.