So if you do not already know this you do not make the same mistake under NO CIRCUMSTANCES DO YOU ASSULT WITH SIEGE UNITS There is NO difference in the damage done by your seige units from the commands "Assult" or "siege" but.... there is a major diffence in the DAMAGE your units take if you "assult" with you take full damge if you siege you take only a fraction of the damage
Definition: Siege – A Siege is a prolonged series of attacks on a city. The troops you send out will continue to attack the city in hourly waves until destroyed or recalled. Each wave deals 1/5 of the damage an assault would deal both to the attacker and the defender.
So assulting with siege is pointless as u gain nothing from it and open your siege units up to taking unneed damage and getting killed