In my opinion, saying "I'm about to do something" implies that an action is going to take place in the near future, while "I'm going to do something" implies that an action is going to take place in the general future (no time indication). For example: A: What are you doing? B: I'm about to clean the kitchen. < Person B will clean the kitchen very soon or as soon as the conversation ends. A: What are you doing? C: I'm going to clean the kitchen. < Person C will clean the kitchen, but there is no definite time frame.

Yes, there are many ways to say the two following phrases. :) "I'm going to do something" is usually said when the person is planning ahead of time. Ex. -I'm going to go to the store to buy some candy. -I'm going to drive to the beach with my friends. -I'm going to study for school. "I'm about to do something" is usually said when in the moment. Ex. -I'm about to play soccer with my friends, -I'm about to speak with him on the phone. -I'm about to do yoga.

No difference really, welcome to the English language bud.