Two endings, one meaning
Si tuviera tiempo and si tuviese tiempo are the same sentence: same meaning, same time. Both sets are standard, and you can even mix them within one text. It works like English dreamed and dreamt: two forms, one meaning, neither wrong. This lesson is about which set you pick — and where you have no choice.
The same sentence with both endings
Si tuviera más sitio, me quedaría el sofá.
If I had more space, I'd keep the sofa.
The form you hear in conversation.
Si tuviese más sitio, me quedaría el sofá.
If I had more space, I'd keep the sofa.
Identical statement, more formal ring to it.
Me pidió que le escribiera un correo.
She asked me to write her an email.
Me pidió que le escribiese un correo.
She asked me to write her an email.
Who says what
-ra is clearly more common. In Latin America you hear and say almost only -ra in conversation. In Spain -se is better represented, above all in the north, in press and literature, and in formal texts such as contracts. The -se form sounds more elevated and closer to writing; in casual talk it stands out, the way whom does in English.
Where -ra is practically the only form
quisiera, debiera, pudiera
Quisiera is a fixed politeness formula (I'd like), not a freely interchangeable subjunctive form: nobody says Quisiese un café. Likewise debiera stands in for deberías and pudiera for podría; there too it stays -ra.
Quisiera reservar una mesa para el sábado.
I'd like to book a table for Saturday.
Quisiéramos hablar con el responsable.
We'd like to speak to the person in charge.
Debieras avisarle antes de ir.
You ought to let him know before you go.
equivalent to deberías avisarle
hubiera instead of habría
In the main clause of a past unreal conditional (the I would have gone half), hubiera often stands in for habría. There -ra is the usual form; hubiese is possible but rarer. Inside the si clause both forms are equivalent.
Si me lo hubieras dicho, hubiera ido contigo.
If you had told me, I would have gone with you.
hubiera ido stands here for habría ido
Me hubiera encantado verlo en directo.
I would have loved to see it live.
