There is an archaic business of "i" formats like 720i. This is essentially obsolete. What used to be done is that odd lines were in one frame and even lines were in the next. This reduced the required bandwidth back in the days when moving data was a challenge.
There is plenty more, you have file formats (like mp4 or others) as well as encodings (h264, h264, avcd, ...).And then there is the whole business of playback frame rates (24, 25, or 30 fps ... or more!)
Also lurking is the business of 4:2:2 designations that seem specific to encoding over HDMI. And we can talk about whether we have 8 bit video or 10 bit video with less or more colors.
I just uploaded a video to Youtube and found that it was playing at 720p, but I could click the settings gear and get it to play at 1080p -- which is how I shot it.
Tom's Digital Photography Info / tom@mmto.org