Implying that it was an effort, but you are welcome to it. Whereas “no problem” denotes that the effort is was not a problem for me to do. I use them interchangeably - “you’re welcome” as a response to a complement, or something where there was moderate effort put into the task; “no problem” when the task was low effort (“Thanks for responding to that email so quickly”) or I feel my effort was obliged (helping pick up after a meeting).