read the full article hereOVERALL HD FORMATS:
"HD" is a general term and it covers all the Hi Def formats including HDV really. But most people, at least most working professionals in film or broadcast, when they are referring to HD are talking about material acquired on HD Vision, HDcam, DVCProHD, Viper, or HDcam SR (or acquired on film and converted to one of those formats) using a picture size of 1920x1080 or 1280x720 and color sampling of at least 4:2:2 (HDcam is 3:1:1, but that's the exception).
COMPETING HDV FORMATS:
HDV refers to a tape format that was really designed to be the replacement for DV, but for once the industry replaced a format with another format that uses the same tapes...hurray! On a DV videocassette, you can get two types of HDV footage: 1440x1080 frame size (as opposed to HD formats with 1920x1080), which has the same data rate as DV (25 megabits per second) but uses MPEG compression to create 15 frame (NTSC successor); or another popular HDV format uses 12 frame (PAL successor) groups of pictures or "GOPs." The basic compromise here is image quality as the image compression is very aggressive, a necessity to fit that much picture on a DV cassette.
some great tips on shooting HDV
some top DV and HDV cameras compared