Anuncio vs. comercial
While both terms describe advertisements, anuncio is a broad, all-encompassing word used for any medium, whereas comercial is a specific term used primarily in Latin America for television and radio spots.
Anuncio
A2This is the general term for any announcement or advertisement. It applies to TV, radio, newspapers, billboards, and the internet. In Spain, this is the standard word for a TV ad, as comercial is rarely used there.
Ayer vi un anuncio muy gracioso en la televisión.
(Yesterday I saw a very funny ad on television.)
El periódico está lleno de anuncios de trabajo.
(The newspaper is full of job ads.)
Tienes que esperar a que termine el anuncio para ver el video.
(You have to wait for the ad to finish to watch the video.)
Pusieron un anuncio enorme en la autopista.
(They put up a huge billboard ad on the highway.)
Comercial
B1This term specifically refers to an audio or visual advertisement broadcast on television or radio. It is widely used in Latin America to describe the advertising break that interrupts a program.
No me gustan los comerciales que interrumpen la película.
(I do not like the commercials that interrupt the movie.)
Vamos a una pausa y regresamos después de unos comerciales.
(We are going to a break and will return after a few commercials.)
Ese comercial de radio tiene una canción muy pegajosa.
(That radio commercial has a very catchy song.)
Los actores grabaron un comercial para una marca de refrescos.
(The actors filmed a commercial for a soda brand.)
Summary
Use anuncio for any type of advertisement (print, digital, or broadcast) and as the preferred term in Spain. Use comercial specifically for TV or radio breaks, particularly when speaking Spanish in Latin America.