Impedance, floating

What's the difference between impedance and when a pin on a microchip is floating?

I get the basics of impedance. I'm capacitive impedance it's a build up of charge. Like air in a balloon. In resistive impedance it's a build up of the magnetic field, like a flywheel.

A floating pin isn't connected to anything reference voltage so it can fluctuate with surrounding interference or whatever.

Why do some ICs have tri state, low, high, and high impedance? Isn't high impedance the same thing as floating?

If it is high impedance that means it had to be connected to something, right? Don't Some kind of big capacitor or inductor in the chip?