In Do Not Disturb mode, the phone will not ring or send notifications until you explicitly dismiss them. This is typically used when you are not available to answer calls or you are in a quiet place and want to avoid disturbing others. Bedtime mode, on the other hand, is the default mode for notifications on the phone. It sets a timer for a set amount of time and sends notifications only when the timer has expired. This is typically used when you want to avoid being disturbed by notifications and want to get a few hours of sleep.