Topic: FA 2.3.26 to FA 2.4.2+ DB Schema Synch
The sql/alter2.4*.php files are there to migrate the data into the new fields/tables and the FA web user interface is the correct way to upgrade an FA install.
To compare the standard chart differences and sql statements needed to synch the database from FA v2.3 to FA v2.4 we can use the online tool at http://www.infoom.se/compare-mysql-online/ by pasting the FA 2.4.2+ sql/en_US-new.sql's contents in the upper textbox and that of the FA 2.3.x counterpart in the lower textbox and click "Compare".
Attached is the current state.