IQ-based technological skills represent a studied technical understanding of the specific methods and tools common at a particular TL. There is a penalty to your skill roll when you use these skills with the equipment of a higher TL (which relies on scientific and engineering principles unknown to you) or a lower TL (which depends on principles that were, at best, a “historical footnote” during your training).

Technological skills based on attributes other than IQ let you use technology; they do not assume any real understanding of the science or engineering behind the tools. For instance, a TL5 gunslinger accustomed to firing a Colt Peacemaker might find a TL7 Colt Python a bit strange, but he would have little difficulty shooting it.
For skills like this, apply a flat penalty of -1 per TL of difference between the skill and the equipment. For instance, a TL5 gunman would be at -2 to shoot a TL7 revolver. It is irrelevant whether the equipment is more or less advanced – a TL7 policeman would be at -2 to fire a TL5 revolver, too.