Their subpoenas are different. i.e. they're not the same as a legal subpoenas. His argument is that they don't have the "force of law". Which would be correct except they have the "force of the constitution". Many times a court won't hear cases regarding these subpoenas because it's a political thing and not legal. I suspect they only get involved if it's actually about the powers given out in the constitution. i.e. you refuse to provide information to a group who has the power to get that info under the constitution so they can do their job, then they would hear the case and rule against you.

The problem is that because of the overlap of terminology, people assume it's all just like the legal system with law backing it up. It's not. They're a completely different beast.

The result of not complying could be different but for both, "obstruction" is a typical one which is exactly what the congressional subpoena he was talking about says in it. Don't provide the documents, then you can be "charged" with obstruction. In this case it would get added to the impeachment. I did hear something else about what they could do, some sort of special "jail". But I haven't researched that at this point. It's the first time I've ever heard that there is something like that.