The one major difference I've noticed as a teacher is that gifted kids who do not have ADHD appear to not be paying attention. However, they likely can tell you what you said, what it was about and answer the question, all while reading a book, fidgeting and humming.
Nice to hear this comment and from a teacher also! DS will be singing and doing gymnastics at the same time and yet he not only will know what I was saying to him but will be able to interject himself (appropriately) into the conversation his sister is having with her step-dad in the next room. As he likes to say - "He is the ultimate multi-tasker." What I would like to see is an activity that is so engaging it stops the humming, foot tapping, cartwheeling. Sigh...........