I been watching some videos on how to do the batting and backing. I am more confused now then ever!!

Some videos show that the batting and the top are the same with no extra batting showing around the edges of the top. Then I see another video where the batting is bigger than the top. So, which is it? I know that the backing has to be bigger then both batting and top.

Any help would be greatly appreciated for this new quilter.

Thank you,