I would tend to use "has retired" about someone who has just recently taken retirement, whereas I'd say "is retired" about someone who has been retired for some while. However, since it's common to abbreviate both, particularly when speaking, to "He's/she's retired, who's to know!?
HavardF is correct. It is the difference between two sentences which convey the same meaning. But since we are learning grammar, here it is:
- Mon père est à la retraite = My father is retired (but is also understood as "my father (has) retired")
- Mon père a pris sa retraite = My father (has) retired.
I think it's like "à la mode." If you just say "Mon père est la retraite," you're saying your father is the retirement, as though he were a place. If you add the "à," like in "à la mode," you make a noun an adjective, so "the fashion" becomes "fashionable" or "the retirement" becomes "retired."
That doesn't make any sense. This is just a case of different prepositions, and Duo's insistence on the shortest English translations.
You can say "He is IN retirement." in English, but they simply use a different preposition in French:
'La mode' = 'Fashion', 'À la mode' = 'In fashion'.
'La retraite' = 'Retirement' (Notice we would never say THE retirement), 'À la retraite' = 'In retirement'.
That was my first translation as well but apparently 'retired' is the way this phrase is most commonly understood: http://context.reverso.net/translation/french-english/%C3%A0+la+retraite.
I looked it up. Retraite literally means retreat. À la retraite means in retreat. "My father is in retreat" is the literal way to say he is retired.
Kinda cool! The literal English of retire is "go to bed". I would rather think that in a few years I will be in retreat, not going to bed.