Hi Ben,

In almost all cases, they're effectively the same. readOnly is true for fields that won't change after the row is inserted, such as auto-incrementing RowId fields. userEditable is false for fields that the user isn't allowed to edit directly. There are a few cases when a field might not be readOnly, but is not userEditable, such as the LSID column on datasets. It can change if the date or participant/subject value changes for the row, but it's automatically updated by the system and can't be set directly to an arbitrary value by the user.

Thanks,
Josh