Transactional messages alert you on a recent transaction. For ex: Withdrawal of cash, card swiping etc., Promotional messages are sent to promote an event or a marketing campaign like offers and discounts, promo codes etc.,

Transactional SMS Promotional SMS
6 characters Sender ID Only numeric Sender ID
Can be delivered 24/7 Can be delivered only between 9 AM to 9 PM
Can be delivered to all the numbers You can not send promotional sms to DND (Do not disturb) numbers
Ex. Dear customer your account balance is Rs 55555. Regards. ABC Bank. Ex. Now get 4.5% interest on all your fixed deposit. Regards. ABC Bank.