There are more than one way to view the description of the universe as flat. There is the description of an open, flat or closed universe in terms of it's fate, expansion forever away from gravity, or a big crunch.

Then there is the description of our observable universe being flat in it's geometry, or is it that there is no way to measure the tiny curve of space in our part of the sphere.

Another probably wrong idea is that the entire universe is flat. Are these things confused, even by the experts?