I think it's safe to define "gifted" as a certain level of thinking power above the average. On a good day a current IQ test would mark that power at 130 or higher. People are complicated, however, so when you take that measurable thinking power and blend it into everything else that makes us human, especially our social and emotional needs, you get an infinite variety which explains the diversity of the gifted population. Throw in variables like motor skills, working memory, and processing speed, and it's obvious that each gifted person is totally unique and there are no manuals.
I like to imagine we are like those graphic audio equalizers on your PC, but replace the frequencies with different areas of thinking and feeling and personality. An average person has most of these on a similar level across the board. But as you enter the gifted range, the levels almost never go up together; things become asynchronous, so one person has a high working memory, but lower verbal, and vice versa. And just how in audio this brings unique, often distorted sound, so with people it brings unique gifts and talents but often at a cost of emotional and social problems during development. You can imagine what some of the so-called "idiot savants" might look like on such a graphic equalizer, with one or two levels at the top and then others at rock bottom.
In my opinion, working and long term memory are vastly underrated in measuring intelligence. Raw thinking power is like having a muscle car with no roads. If you're constantly having to rebuild the roads, look up the facts, then your muscle car isn't all that useful or fun.
I think that explains why the only people I've ever met who seemed impressively and universally intelligent to me all had a superior memory. I worked with one IT guy who had 40 certifications and remembered everything. He was a mellow guy, not intense or "giftie", but he just could remember everything. For all I know his thinking power could have been average but what does it matter? His brain was finely mapped with smooth roads and excellent signs, so even if he was driving a Honda Civic, the guy next to him with the muscle car brain was constantly popping his tires and having to repair the roads and squint at the signs his poor memory obscured.
OK, my analogy is breaking down at this point but that's because according to the IQ test I took when I was 17, my 8-yo daughter is smarter by 25 IQ points!
