Key difference: YouTube currently allows users to watch videos in various resolution sizes, as suitable to the viewer. HD and HQ are two different formats available for viewing videos on YouTube. HD stands for high-definition, whereas HQ stands for High Quality.

In YouTube, people have the option to upload their videos in order to share them with the world, or people can view the videos uploaded by others. YouTube currently allows users to watch videos in various resolution sizes, as suitable to the viewer. HD and HQ are two different formats available for viewing videos on YouTube. HD stands for high-definition, whereas HQ stands for High Quality.

YouTube currently offers resolutions of 144p, 240p, 360p, 480p, 720p and 1080p. The standard resolution that the videos play back in is the 360p. HQ refers to the 480p, while HD is either 720p or 1080p. The resolution is of course depending on the quality that the user may have uploaded. The user may upload the videos in 1080p, while the viewer may choose to view that video in 720p or even 480p.

The higher the resolution; the clearer and sharper the video. If one was to see a 360p video in full screen, the video would appear blocky and unclear. However, if the same video was in 720p or 1080p, then it would be much sharper in full screen. This happens because the HD videos have an increased bitrate and a better resolution. However, also because of this the HD videos take longer to load, as well as occupy more memory.

Still, the standard video, i.e. 360p is more than enough for viewing on smaller screens, such as the screens on smartphones. They are also enough for embedding, as they show a decent enough video but do not take too long or too much memory download to play.

However, in instance where the 360p video is just not enough, there is the HQ, i.e. 480p. The HQ is somewhat of a compromise between standard and HD. HQ has a better resolution than 360p but does not take as much time or memory as HD.

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