Evergreen 2.10.1 is a bugfix release that fixes one significant bug in 2.10.0:

This bug affected only databases that were upgraded to 2.10.0 from a previous version; fresh installations of 2.10.0 are not affected.

Evergreen users who prefer not to perform a full upgrade from 2.10.0 to 2.10.1 can fix the bug by applying the database update script 2.10.0-2.10.1-upgrade-db.sql (found in the source directory Open-ILS/src/sql/Pg/version-upgrade).