Grifo vs. llave vs. canilla
The Spanish language presents a rich variety of vocabulary as it is spoken in different regions of the world. The words 'grifo', 'llave' and 'canilla' all translate to 'faucet' or 'tap' in English, but their usage can vary depending on locale.
Grifo
The most universal term for faucet or tap in Spanish.
El grifo está goteando.
(The faucet is dripping.)
Cierra el grifo cuando te cepillas los dientes.
(Close the tap when you brush your teeth.)
Llave
While also means 'key', this Spanish word is mostly used in many parts of Latin America for faucet or tap.
La llave del agua está rota.
(The water faucet is broken.)
Por favor, cierra la llave.
(Please, close the tap.)
Canilla
'Canilla' is from Rioplatense Spanish dialect, used primarily in Argentina and Uruguay for a faucet or tap.
Hay que reparar la canilla de la cocina.
(We need to repair the kitchen faucet.)
La canilla está abierta, por eso hay tanto ruido.
(The tap is open, that's why there is so much noise.)
Summary
'Grifo', 'llave', and 'canilla' are three terms used to denote a faucet or tap in different regions of the Spanish-speaking world. While 'grifo' is universally understood, 'llave' tends to be used in Latin America and 'canilla' is more typical in Argentina and Uruguay.