Yes, I believe there is a difference in aptitudes - a great
  variety.

  My issue is that of the notion of intelligence as a 'thing'.

  IQ tests like you said, _do_ measure something and it's
  interesting to note the number. But what does it mean? Well,
  several things:

  a) test taking ability which includes all of the skills required
  to take tests in general
  b) a certain type of visual reasoning skills.
  c) a certain type of skill in transforming visual metaphors into
  the kind of semantic logic required to form the expected
  answers.

  In short, reading the minds of the intentions of the test-givers
  based on scribbles on paper tongue emoticon

  "How are they trying to trick me here?" was a constant question
  I had in my head throughout school, including IQ testings.

  I think they overuse "tricks" in testing. One of the nice things
  that happened when I became an adult is that every test I ever
  took for any reason after the age of 18, wasn't trying to fool
  me... at least not in the sadistic manner of educational
  testing.