Freewheel or Cassette Can someone help me, I currently have a 9 speed cassette on my road bike, I would like to get another pair of wheels with larger tyres so I can swap easy depending on where I'm going without having to take tyre off. 
I have found a new set with the correct amount of gears and same brakes but the only difference it says its Freewheel gears. If I have the same number of gears will this work? (Cassette on one wheel set and freewheel on the other wheel set being used on the same bike set up) 

Thank you in advance
If the spacing is the same, it should work, although I wouldn't be surprised if the shifting required adjustment every time you swapped, even if the spacing is nominally the same.

The other problem is that a 9-speed freewheel/hub is an inherently bad design, since more of the axle is unsupported, and more likely to bend or break.

It's also possible that the set you found really does have a cassette and freehub, and was simply mislabelled. None of the majors ever made a 9-speed freewheel, or a thread-on hub for a 9-speed freewheel.