Should I delete my DVD (VOB files) backups?

[Woodstock]

If your friend's files are 1080p, they're not DVD backups, are they? 1080p is Bluray resolution.

[dcoke22]

If your DVD folders are backups of the full disc, the DVD might have different 'extras' than the blu-ray. Depends how much you're into the minutia.

[Johnqmalapert]

MKV is just a container. The actual video file is inside. DVDs are 480p and the actual video files on the disc if ripped raw are .vob files. Blu rays are 1080p and the raw files are .m2ts. MakeMKV will repackage those files into an MKV container (.mkv file). It does nothing to change the quality. It's up to you whether you want to keep those rips as backups. Personally, I backup the entire disc AND the main movie. If for some reason I ripped it wrong, or I change my player, chose the wrong audio file, etc, I still have the full backup. This adds significantly to file storage requirements but also provides peace of mind.