Al revés vs. boca abajo vs. de cabeza vs. patas arriba

'Al revés', 'boca abajo', 'de cabeza', and 'patas arriba' are Spanish terms that can all convey the idea of something being 'upside down'. However, they are used in different contexts and situations to describe the position or state of things or people. Understanding the nuances between these phrases allows for more accurate descriptions and clearer communication.

Al revés

'Al revés' is a general term that means 'upside down' or 'the wrong way round'. It can refer to the orientation of an object or a situation.
Pusiste el cartel al revés.
(You put the sign upside down.)
Creo que este suéter está al revés.
(I think this sweater is inside out.)

Boca abajo

'Boca abajo' specifically describes the position of lying or placing something with its front or face downwards. Commonly used for people, animals, or objects.
El libro está boca abajo sobre la mesa.
(The book is face down on the table.)
Cuando hago flexiones, empiezo boca abajo.
(When I do push-ups, I start face down.)

De cabeza

'De cabeza' refers to being upside down with the head pointing downwards, often implying an inverted vertical position or diving headfirst into something. It's commonly used with people than objects.
Los murciélagos duermen de cabeza.
(Bats sleep hanging upside down.)
Se tiró de cabeza al agua desde el trampolín.
(He dove headfirst into the water from the diving board.)

Patas arriba

'Patas arriba' often implies a state of disorder or chaos, as if something has been turned upside down and tossed about in disarray. It can be used both literally and figuratively to describe places or situations out of order.
Después de la fiesta, la casa quedó patas arriba.
(After the party, the house was left upside down.)
No encuentro nada en esta habitación; está todo patas arriba.
(I can't find anything in this room; everything is topsy-turvy.)

Summary

While all four Spanish phrases translate to some form of 'upside down', their use varies based on context—'al revés' is for orientation reversal, 'boca abajo' describes a downward-facing position, 'de cabeza' indicates hanging by the head, and 'patas arriba' suggests chaos or disarray due to inversion. By choosing the appropriate expression, one can more accurately describe the specific way in which something is overturned or flipped around.