I believe the Dura Ace one is metal, the Ultegra is plastic. In terms of weight, they're the same. But when you go to use them, you will notice that alloy one gives a firmer feeling. It's similar to the difference between tightening down alloy handlebars vs carbon handlebars, with alloy, the bolt stop is quite clear and firm, where as with carbon you can just keep cranking until you overtorque and crack the bar.
There's a Type A and Type B. Those both look like a Type B.
I think earlier model spindles had shorter internal threads. If you have the deeper threads I guess you could use either fixing bolt. If you have the shallow threads you'd need the short bolt.
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