The "p" in 480p stands for progressive scan , meaning all lines of the frame are drawn in sequence. This reduces flickering and "combing" artifacts compared to the older interlaced (480i) format.
Many Android tablets are limited to 480p if they lack Widevine L1 certification, which is required for HD playback of copyrighted content. [@MY_Update] 480p
According to YouTube Help, creators should set their videos to "Unlisted" or "Scheduled" to ensure the high-definition versions are ready before the public sees them. 2. Device and DRM Limitations The "p" in 480p stands for progressive scan