What Does MiniDVD Mean?
MiniDVD refers to two separate formats. One is a pseudo-format which uses 80 mm CD-R(W) to store content with the same structure as the standard DVD-Video in order to fool some standalone DVD players to treat it as a standard DVD. The other format is a real DVD format, but in a smaller 80 mm size, which can hold 1.4 GB of data compared to the regular 120 mm disc that holds 4.7 GB.
Techopedia Explains MiniDVD
The term MiniDVD is used to refer to two formats that may be considered interchangeable in some ways, but are actually two different technologies. The first is the miniDVD (usually written with a lowercase "m") or cDVD, because it is a regular 80 mm CD-R(W) and not an actual DVD. The only relation to DVD that the miniDVD/cDVD is intended to be played on DVD players. This is done by formatting the content of the disc into the DVD-Video structure specification in order to fool some standalone DVD players. Although the disc can only contain about 700 MB of data, it can store up to two hours' worth of video by using non-standard resolutions, more B-frames, long GOPs and high compression rates.
The other format is the MiniDVD (with an uppercase "M") or small DVD that can contain up to 1.4 GB of data for single-sided discs and 2.8 GB for double-sided discs. There is not any difference in data format to actual 120 mm DVDs, only the size and the resulting lower storage capacity.