Se lava la cara vs Ella lava su cara
 

1. Se lava la cara dos veces al día.

2. Ella lava su cara dos veces al día.


Creo que entiendo la diferencia pero #1 parece que ser mas comun pero #2 parece mas claro.


To us gringos trying to learn #2 seems so much more reasonable.

The sentences don't mean the same thing.
The first has no subject. If we assume 'ella', since that is given in the second sentence, 'ella' washes her OWN face.
In the second sentence, 'ella' washes someone ELSE'S face.

The verb 'lavarse' is reflexive. The action reflects back on the subject. That explains why a native speaker uses the article 'la' instead of the possessive adjective 'su'. (There's no need to reiterate that the face being washed is one's own. The verb makes that distinction.)

The verb 'lavar' is not reflexive. The action is directed towards another person.
That's why the possessive adjective is necessary.

In the second sentence she may be washing her own face, but it doesn't sound natural, because we prefer using the reflexive form. :)

In #1 how do we know if "He", "She" or "It" washed their face?



Gracias como siempre.

We don't, unless the subject was already mentioned (in context). Add "You (formal)" to your list of subject pronouns. It also takes a third-person conjugation.

Gracias. Despues de pensando mas entiendo.

Ella lava su cara dos veces al día is used in some Latin American countries I believe.:worried: