The name of a Polish pastry? Chrust?

What's the difference between "ciasto" and "placek" - are they equivalent in everyday Polish?

Ciasto can be cake, dough or pastry. Generally baked. Placek can be used for a few other things like latkes (placki ziemniaczane), things made with batter etc but not only those. Not usually baked but can be.

The terminology isn't always precise.

I thought that the Polish "babka" was often called "placek" but it may depend on regional customs in Poland.

I'd call that cake, though yes, there may be a regional aspect.

Over the years, I've heard a lot of things called placek/placki, thinking about it, though not a cake that's baked and rises as far as I can remember.