In the leftmost column you see all tags supported by Picard in some way, the second column shows the tag's internal name (the one used in tagger script). All other columns show if and how this tag is saved to the different file formats. For MP4 the entry for original date and year is empty, which means it is not saved.
Some explanation why this is the case: Originally Picard was very conservative when saving tags. It only saved tags to files if for the format there was either an existing accepted standard way of storing this tag or at least the big popular players such as iTunes where using some custom tag. But with the exception of MusicBrainz IDs Picard did not make up any tags. For MP4 this basically means Picard followed the iTunes Metadata Specification.
This changed a bit in recent years and Picard now writes more tags to files. A lot of MB users are using players flexible enough to handle custom tags. Still not every tag for every format is supported.