It's really the experience in totality. There are choices, but for someone new to the Java ecosystem, it's confusing why and why should I care. Because in the end, I don't care. I just want to use Clojure, but there's decisions to be made at every step of getting going that aren't clear to someone new to the ecosystem.
This same thing happened with .NET as well. At one point in time, there was .NET Framework, .NET Core, and Mono and a question of how to get F# in all that. That was just as, if not more so, confusing. However, it's since been cleared up: install .NET 6 or higher.
I know it’s mostly about a sentiment, but if you or anyone is curious — there is basically none, OracleJDK is a fork of OpenJDK (which is the reference implementation) with basically negligible changes. License wise OpenJDK uses the same one as Linux so you can use it as you seem fit, while the current LTS OracleJDK (17) is free to use until the next LTS release + 1 year, but unless you need corporate support, you really have no need for that.