The protocols for the locks are different. Finding a free mooring on the river is much more difficult. And the river is much wider and deeper.
But after nearly a week on the Thames the biggest surprise is to find people swimming. You spot a couple of things bobbing about in the water, not far from the bank and you might wonder whether they are ducks or geese, even though they don't look quite right.
They turn out to be swimmers - and these swimmers are not unusual. Apparently people swim the whole length of the river as a badge of honour.
People don't swim in the canals.