Both are the "Falcon 9 Block 5" version. Earlier in the Falcon 9's history they were constantly iterating on the design, but NASA's certification for human spaceflight required them to make seven flights on the same design.

So it's both a proven design, and they're reusing one that has flown before. But not the most heavily reused one.

https://en.wikipedia.org/wiki/Falcon_9_Block_5

https://en.wikipedia.org/wiki/List_of_Falcon_9_first-stage_b...

Note that even within Falcon 9 Block 5 there are changes to make reusability easier and cheaper. The earlier Block 5 are not as easy to reuse as later Block 5. ("Pain in the ass" as mentioned in Elon in the conversation with Tim Dodd[0])

[0]: https://everydayastronaut.com/starbase-tour-and-interview-wi...

B1062 is the serial number of a particular booster that SpaceX has in its fleet of boosters. So "the same physical thing", as in "we are flying the plane with this particular tail number"

Yes, what you said. Sorry to the above, I should have been clearer.

I'm so deep into the rocketry nerd-world I've fallen victim to this xkcd: https://xkcd.com/2501/

Haha no worries. Is it obvious that a rocket run 10 times is safer than a rocket run 2 times? To my uninformed mind I would think there's an obvious tradeoff in proven functionality vs. accumulated damage from launches.

They are reusing the same physical engine.

They're reusing the whole rocket, not just the engine. In many SpaceX launches, you can see the carbon deposits left on the side of the rocket from its previous flights.