Question on Video Resolution on Pioneer Plasma

I would like some to better understand video resolution.

I own a 3 years Pioneer PDP-5071HD Television. I was looking up something the other day and the manual gives the # of pixels as 1365 x 768.

I know that this is not 1080 resolutions but this is more than 720. Also the TV will state that is displaying 1080i and 1080p signals at times.

Can someone please explain this to me? Also we love the picture but would it be worth moving onto one of the newer Panasonic Plasmas?

Thanks