Although ID3v2.4 is the latest version, its support in music players is still lacking. While some software has no problem using version 2.4 tags, others may not be able to read the tags and display the information. Support for ID3v2.4 in other media players (such as smartphones) is variable.
Other than native support for multi-valued tags in v2.4, the Picard Tag Mapping section will show you what you lose when choosing v2.3 instead of v2.4.
ID3v2 text encoding
The default for version 2.4 is UTF-8, the default for version 2.3 is UTF-16. Use ISO-8859-1 only if you face compatibility issues with your player.
Join ID3v23 tags with
As mentioned above, ID3v2.3 does not support multi-value tags, and so Picard flattens these to strings before saving them to ID3v2.3 tags. This setting defines the string used to separate the values when flattened. Use ‘; ‘ for the greatest compatibility (rather than ‘/’ since tags more often contain a ‘/’ than a ‘;’) and for the best visual compatibility in Picard between ID3v2.3 and other tagging formats.
Save iTunes compatible grouping and work
Save the tags grouping and work so that they are compatible with current iTunes versions. Without this option grouping will be displayed in iTunes as “work name” and work will not be available.
See the Picard Tag Mapping section for details.
For other players supporting grouping and work you might need to disable this option. MusicBee is one example of this.
Also include ID3v1 tags in the files
This is not recommended at all. ID3v1.1 tags are obsolete and may not work with non-latin scripts.