You said "Are you all kidding me??"
Not at all ! ... I know you are an expert on insects and me not at all , I just wanted to understand a little bit more on differences. I looked the links you gave me, but it is not easy at all when we are not familiar on biology.
But I took note of your advices :-)

Just found this new post on hoverflies : @dannewton/insect-portrait-project-hoverflies