From memory, I think the runtime is pretty standard, what you got was a more restrictive environment in which the CLR and Framework can run so you had less chance of clobbering data, hanging SQL processes and shooting yourself in the foot.....unless you really, really needed to.
No, SQL Server just uses the normal .NET Framework to execute managed code which is also implied by the name of the feature, Common Language Runtime (CLR) Integration. Well, maybe one could also read this as integrating - in the sense of implementing - a CLR into SQL Server.
Yes, SQL Server hosts the .NET framework runtime but with added security configuration. There are also other applications hosting the framework (like IIS), and you can actually host the framework yourself (both the full and core framework). I was actually playing with the idea of hosting .NET addons in Kodi but it turns out it is too much work for a single developer as a hobby project.
What would be the advantage of .NET Kodi addons over Python? They would be faster that's for sure, but if I understand it correct, addons are not the main reason of Kodi suboptimal performance. The downsides are obvious - while you can relatively easy skim over the source code of the Python addons, it wouldn't be easy with .NET binaries - and most of the addons wouldn't provide source code. And the regular user can easily hack the feature, fix or two into Python addon code by himself, that wouldn't be so easy with .NET addons.
https://docs.microsoft.com/en-us/sql/relational-databases/cl...
https://docs.microsoft.com/en-us/sql/relational-databases/cl...