[HiTech RedNeck]

I don’t know how close it has to get in order to count, but here’s a humongous Catholic Church building that has the portico and steeple treatment:

http://www.stpetschurch.org/

Is it a matter of internal layout that is the difference?

[markomalley]

Most traditionally-designed Catholic churches have a layout that is something like this:

You'll note the cruciform shape, right away. Most classically designed churches maintain that in one fashion or another (even though it might not be immediately apparent).

Without going into a bunch of detail that you may or may not be interested in, the function of each of the areas somewhat parallel the different areas in the temple in Jerusalem. You can also trace some of this in Rev 5 - 7 as well.