If’ usually introduces conditional clauses. The same applies to other conditionals such as unless, should and in case which, however, perform other functions in different contexts.

With this combination we are contrasting an imagined or real event in the ... can also convey the same idea of past event and present result by using type 3 conditional (if + past perfect, would ...

With the third conditional, Elena, we are often talking about something that might have happened, but didn't. As your example illustrates, when we are discussing such past situations we normally ...