576p is a video mode that can display 576 scanlines per frame.
Total resolution is thus 576 pixels in height, at least in theory.
(There is always an undisplayed margin.)
PAL interlaced is a resolution that can display appx 512 lines but only by showing 256 per frame period, with alternate frames shifted half a line height so as to 'fill in the blanks' of the previous one. Total resolution is thus 512, but flickering at 25Hz in all regions where alternate frames have contrasting pixels. (50Hz elsewhere)
PAL non-interlaced has exactly the same line timing and almost the same frame timing as interlaced PAL, except for the halfline shift between frames which is skipped. So this mode 'paints over' exactly the same pixel positions in every frame. Total resolution is thus 256, without interlace flicker. (Though still with 50Hz flutter.)
Btw: The total number of raster lines per frame for PAL is 312.5 for interlace and either 312 or 313 for non-interlace. So traditional TV wastes a lot of raster lines which never are visible. Similar relations are true for NTSC, with its 262.5 vs 262/263 raster lines per frame of which only 224 are visible giving resolutions that are 448 or 224 pixels high for interlace and non-interlace respectively.
Best regards: dlanor