Yes, thanks epoh. It's a big help. I understand what you're saying. I agree that ADHD + giftedness complicate matters and there seems to be overlap between the two.
It's possible my son has ADHD because he does show some characteristics of it; my son needs the prompts to get him to the table for breakfast or dinner but not to get dressed or put on his shoes most days. Still, he is also showing characteristics of being pg and that seems to be the stumbling block for us.
What's annoying for us is that private gifted school #1 was specifically for kids with ADHD and executive functioning issues and they didn't want to accommodate him because they thought he was pg (with ADHD perhaps)! Private gifted school #2 has a lot of kids with ADHD but takes a less structured approach to the issue, but even they have been stumped at times.