Instead of saying that their meanings differ, I think it's better to say they have different uses. That means they are each likely to be found in different contexts.
Instead of saying that their meanings differ, I think it's better to say they have different uses. That means they are each likely to be found in different contexts.
English speakers naturally foreground new information in main clauses and place given information in the background in subordinate clauses.
I arrived there in the morning and stayed awhile. He came when I was there.[given info: my being there; new info: his coming] He came early in the morning. I was there when he came.[given info: his coming; new info: my being there]