Following is general meaning, it can change in different circumstances
Audit Procedures — General term, it means any audit related activity
Further Audit Procedures — Test of Controls & Substantive Procedures
SAs specify standard audit procedures from different situations like existence of inventory, opening balance etc
Additional Procedures — Perform more audit procedures apart from standard audit procedures
Alternate Audit Procedures — In some circumstances standard procedures are not applicable or difficult to apply or management didnt allow them etc so they specify alternative procedures, so dont perform alternative audit procedures instead standard audit procedures