{IC pins} Leave Floating vs Leave Open?
I believe...

Leave Floating : Is meant for inputs. The pad is literally floating and is free to receive whatever noise is buzzing around your circuitry. Generally not a good idea for CMOS parts unless dictated by the part spec.

Leave Open : Is for outputs.
The pad on "Leave Open" is being driven by the pin if the pin is active.

Which term you use for bidirectional pins is debateable. I'd assume because the input side is always active "Leave Floating" would be the prime suspect.