Despite all that effort, he’s wrong as well. I’m born and raised in London, UK and we most certainly have differentiations. The description of preserves having elements of the real fruit is the same in the UK: I can go to the local supermarket right now and the shelf will have different sections for jams, preserves, and marmalades (which the person they were replying to were also correct in their description).
The thing I haven’t seen is American Jelly, as Jelly here is the same as Jell-O in the US.