ala Ken, I will just copy and paste from other sites. Hope this helps.....
HDTV:
* 720p - The picture is 1280x720 pixels, sent at 60 complete frames per second.
* 1080i - The picture is 1920x1080 pixels, sent at 60 interlaced frames per second (30 complete frames per second).
* 1080p - The picture is 1920x1080 pixels, sent at 60 complete frames per second.
Interlaced Scanning
In a television display, interlaced scanning refers to the process of re-assembling a picture from a series of electrical (video) signals. The "standard" NTSC system uses 525 scanning lines to create a picture (frame). The frame/picture is made up of two fields: The first field has 262.5 odd lines (1,3,5...) and the second field has 262.5 even lines (2,4,6...). The odd lines are scanned (or painted on the screen) in 1/60th of a second and the even lines follow in the next 1/60th of a second. This presents an entire frame/picture of 525 lines in 1/30th of a second.
Upconvert
The term used to describe the conversion of a lower apparent resolution to a higher number, such as "up-converting" 720p to 1080i. This is a misnomer, though, since to accomplish this, the horizontal scanning frequency is actually lowered from 45kHz to 33.75kHz. Resolution quality is not improved by this method.
HDTV:
* 720p - The picture is 1280x720 pixels, sent at 60 complete frames per second.
* 1080i - The picture is 1920x1080 pixels, sent at 60 interlaced frames per second (30 complete frames per second).
* 1080p - The picture is 1920x1080 pixels, sent at 60 complete frames per second.
Interlaced Scanning
In a television display, interlaced scanning refers to the process of re-assembling a picture from a series of electrical (video) signals. The "standard" NTSC system uses 525 scanning lines to create a picture (frame). The frame/picture is made up of two fields: The first field has 262.5 odd lines (1,3,5...) and the second field has 262.5 even lines (2,4,6...). The odd lines are scanned (or painted on the screen) in 1/60th of a second and the even lines follow in the next 1/60th of a second. This presents an entire frame/picture of 525 lines in 1/30th of a second.
Upconvert
The term used to describe the conversion of a lower apparent resolution to a higher number, such as "up-converting" 720p to 1080i. This is a misnomer, though, since to accomplish this, the horizontal scanning frequency is actually lowered from 45kHz to 33.75kHz. Resolution quality is not improved by this method.