Okay... as far as I am aware it's 1024 x 576. I have been editing for many many years and when working in PAL Widescreen it has only ever been this for me. I have always however worked with Adobe and one thing I would note is this. Sometimes video in the 16x9 format have black handles at the horizontal sides of the picture. This could explain the issue with the ratio differences? Black handles are sometimes added specifically so that nothing from the side of the picture is masked off when viewed on TV which naturally cuts off the edges of the picture (hence action and title safe areas). Now that everything is moving towards HD, handles are no longer being used it seems even on SD widescreen footage.
That probably doesn't clear it up... but that's my two cents anyway!