Does Rope Trick create an extradimensional space, or does the space already exist?

In my answer to this question, I used the fact that Rope Trick states

…an Invisible entrance opens to an extradimensional space that lasts until the spell ends.

After thinking about it for a while, I started to wonder if I was wrong. This sentence can be taken two ways – either the entrance lasts until the spell ends, or the extradimensional space lasts until the spell ends.

The text

Anything inside the extradimensional space drops out when the spell ends

implies that the space ceases to exist when the spell ends. But this is different from similar destruction of bigger-on-the-inside spaces, such as the Bag of Holding:

If the bag is overloaded, pierced, or torn, it ruptures and is destroyed, and its contents are scattered in the Astral Plane.

So… Does the space get created and cease to exist when the spell ends, or is it the entrance?