The biggest difference with tube cameras is that they have a light streaking effect:
As reverselandfill said, this can create interesting results with feedback.
In addition to old professional gear, there are many smaller early consumer camcorders that use tubes instead of CCDs. But as prakodr mentions, they often use connectors/jacks that are non-standard, at least to connect the cameras to the oft-separate recording units. Finding all the correct cables/adapters, power supplies, etc. can be difficult.
Sometimes searching for the tube names (newvicon, vidicon, etc.) yields some good results on Ebay — though also, if people know what tubes are inside, they are more likely to be asking higher prices. At very least, I have found that can be a decent way of discovering which old camcorder models are tube-based.