Hesperis, yes, they are same pitch class, but a second is used as a "suspension", while a ninth is an ordinary chord tone in tertian harmony. I would be somewhat surprised to learn that this is different in Canada.

It looks like you've misunderstood what I meant by "ninth with no seventh". Maybe this will help:

C9 -- C E G Bb D

C sus9 -- C F G Bb D

C add9 -- C E G D

The "add" designation indicates no seventh. If the seventh is intended, then no further descriptor is necessary; "C9" implies the chord contains a seventh.

It really has nothing to do with piano v. guitar, or the number of notes possible on a particular instrument, these are just rules of naming, not performing. Voicing will vary, depending on whether it's a piano, guitar, horn or string section, whatever -- naming does not.
Yes, I understand how suspension is used in common-practice period music, like Mozart, the term "suspension" derives from the way these tones function in that music. In modern pop music, though, the resolution is not always made, the name remains, but the function is not always observed.
There are, of course, no ninth chords in the common practice period. You may find instances, for example, of the note "D" appearing over a C chord harmony, but this is analyzed as an appogiatura, not a ninth chord.
hope this helps a little, I really didn't want to get into this level of detail, as I don't think it's going to be very helpful to Paul S. ;)

Paul S, all you really need to know for pop songs is what I first posted. "Pinball Wizard" is one example of sus chords in a pop song.