CORBA is an architecture with APIs and protocols, built so that applications in any language on any system can interoperate as if they were homogenous. And it was all done at a time when Microsoft was trying to lock people in to only using Microsoft products, not playing well with others at all. .NET is simply a copy of Java, although its creator has only released a CLR for its own operating systems.
That may have been the intent, but the reality is that a client application had to be compiled with the client stub corresponding to the particular object requested. The compilation part clearly indicates that only particular language bindings (most notably C at the time) were supported. Transport was not dns (socket) based. It was a horrible environment to work with (circa 1993-1995). As I recall, it was sometime in '96 (when their patent was filed) that Microsoft finally came out with DCOM. Although they claimed early on that COM could be done over the internet, there was no incentive to do same at the time. My understanding is that the DCOM folks did not take kindly to the SOAP folks suggesting RPC over the net but after a couple more patents issued, that was no longer an issue.