Given the following sentences, what is the difference between the conditional clauses in them?

• If you saw a lion in a thick forest, what would you do?

• If you were to see a lion in a thick forest, what would you do?

I'm asking this simple thing because it's confusing me, since there is no such thing in my native language (it's quite different from English).

I can understand this one (it may be a different question):

If you had seen a lion in a thick forest, what would have you done?

but it's a bit confusing me. In my native language, it's always formulated as follows:

If you would have seen a lion in a thick forest, what would have you done?

Does this make any difference in English?