A baritone horn in American usage is a bugle in the key of G used in drum corps that is usually played by former trombonists/euphoniumists. It has 3 valves and a face forward bell and is the middle voice of a drum corps, between the high sopranos and the low contras. It has a forceful tone, as if sounding like a tenor trumpet.

In the UK a baritone horn, usually shortened to baritone, is a tenor saxhorn in Bb, that is, at trombone/euphonium pitch. It is thus the larger version of other saxhorns like the soprano range Bb flugelhorn and Eb tenor horn (alto horn in the US). In the UK the baritone is found almost exclusively in the brass band.

The instrument name in the United States outside of Drum and bugle corps (modern) is largely a misnomer; the euphonium is commonly confused for the baritone horn. The singular difference in these two instruments lies in the shape of the bore. The baritone horn - a saxhorn - is closer in relation to the trombone and trumpet with a cylindrical bore. The euphonium is closer in nature to the French horn and tuba with its conical bore. Music stores in America who sell instruments as "baritone" and "euphonium" with price differences do so only through branding, as all of these instruments sold are euphoniums, despite the persistent confusion which has led in some quarters to three-valve euphoniums being mistakenly called baritones and four-valve instruments being seen as euphoniums.