73: fairly similar to the 66. It's in the same weight class as a 66. Has a bit more "flex" when pedaling hard, but also has a bit more cushion. I really like these saddles when paired with the rod brake roadster bike. I have an original on my 1962 Raleigh rod brake and another original I cleaned up as a spare. I even rode one for awhile on a Schwinn New World and it went well there. In the end, I prefer the 66 for the Raleigh Sports or Schwinn New World type light/cable brake roadster.
33: this one is not all that similar to the 66. It's very heavy and if you're a lighter rider, it actually will have less cusion than the 66 and the 73 because of its very heavy-duty springs. I weigh 155-60 range and hardly moved the springs at all. It might work better for a heavier rider. It also looks weird on a lighter-framed bike like a Raleigh Sports (it looks like it's "too much" saddle for the bike). It might look better on a big-frame DL-1 or a rod brake roadster. I tend to think you have to be a heavier rider to make full use of this. The saddle leather itself is very wide on this one - if you see one in person you'll see almost everything is bigger and much heavier than the 66. Frankly, I don't think it's worth the extra weight and I much prefer the 73 or 66.