I'm afraid there's more to it than just saying "this is that" !
640 x480 simply describes the pixel structure for example, it doesn't say whether it's interlace or progressive for example.
As a generic guide however;
The term '640x480' implies VGA, 640 pixels by 480 active scan lines Progressive scan.
800x600 likewise implies SVGA, 800 pixels, 600 active lines Progressive
1024x768 is XGA etc...
1280x1024 is SXGA etc...
1280x768 is WXGA etc...
852x480 is WVGA (though there are other resolutions that claim WVGA)
These are all 'PC' Resolutions, HDTV resolutions use different terminolgy and do not appear as 'standard' PC resolutions (i.e. you won't find them in the VESA documentation)
480P generically means 720 pixels by 480 active lines Progressive scan.
720P means 1280 pixels by 720 active lines Progressive scan
1080i means 1920 pixels by 1080 active lines in two 540 line fields interlace scan.
1080P mean 1920 pixels by 1080 active lines Progressive scan.
But it's always important to remember that these are general and without full clarification you can't necessarily be sure of exactly what you will get - As an example, although 480P should have 720 active pixels, there may be 704, 696 or 688 pixels with picture information on them (the others will be black).
Regular VGA can be 640x480 at approx. 60 Hz (frames per second) or 70 Hz or a few other Hz, I still call them all 480p, just that I have to say the frame rate when discussing more than one.
The 1080p for ATSC HDTV has (approx) 24 or 30 frames per second. The HDTV tuner box generally converts it to 1080i @ 60 fields per second. 1080p @ 60 fps is not seen in consumer video except when a de-interlacer near or in the TV is used.
The 480p for consumer video has the same number of total scan lines per second as for PC video. The difference has to ddo with what happens between the end of one scan line and the beginning of the next (horizontal retrace interval) and also the vertical retrace interval. There is the SMPTE timing for consumer video and the VESA timing for PC video. I am led to believe that the 480p with SMPTE timing is called 720x480 and the 480p with VESA timing is called 640x480. Most combinations of equipment -- PC's, de-interlacers, TV's and monitors, DVD players, etc. work OK despite non-matching timings and even a mismatch between expected and delivered 60 Hz vs. 59.94 Hz frame rates. A few combinations don't work even when the frame rate matches exactly if the retrace intervals are not just right.
For each scan rate or "resolution" the time allotted during the drawing of each scan line for the visible pixels is the same whether there are 720 of them, 640 of them, or some other number. Analog monitors neither know nor care how many pixels there were on each scan line, they just try to draw however many there are except that where the pixels are too closely spaced than the circuits or electron beam can reproduce, the pixels are blurred together. Equipment that accepts 720x480 and 640x480 digital video, when it gets 640x480, should use up all the space and not leave a black area corresponding to pixels 641-720.
Component video connections and VGA/SVGA connections are analog. When video is transmitted or stored as digital, the retrace intervals, includging scan lines 481-525 of 480p, are not included, and it is up to the DVD player or HDTV tuner box to create and insert them when regenerating analog video output. Digital video as transmitted via DVI or Firewire connections, also has some kind of code at the end of each frame.
What you said in a nutshell is what most people think about.
Note: 1024 x 768 also comes as 768i in the computer world, rarely but still around.
In addition there is a 640 x 480 that is 480i in the ATSC digital TV standards.
All of: 1080p @ 24 fps, 1080p @ 30 fps, 1080p @ 60 Hz, and 1080i @ 60 Hz are nominally 1920 x 1080. Because 1080p @ 60 Hz is rarely seen except when de-interlaced from incoming analog 1080i, the first number 1920 is likely to be different, being instead that of the pixel width of the de-interlacer.
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