Some aircraft, particularly gliders, have unreliable airspeed indicators when slipping
.. interesting comment .. can you cite any aircraft for which the ASI is much good in a slip situation ? PECs are pretty sensitive to such abuses ..
They are more or less the same thing
I suspect that most of us would have the view that they are exactly the same thing .. albeit used with different intent. It might be useful to revisit your definitions in any case ...