a percussion instrument that is usually beaten with sticks
The jazz musicians had used instruments like the piano, drums, saxophone, clarinet, and trumpet.

A horn is a device that makes a loud noise.
Two cows might vary in size, color, size of horns, ability to survive the cold and amount of milk produced.

a small instrument that makes a sharp sound when blown
She grabbed the whistle out of her bag and blew it hard three times.