I don’t know if you’re still looking for an answer, but here are some thoughts.
I’m assuming you took the 2017 test. I think the Lang exam is experimenting more with research papers (more formal nonfiction writing). I had trouble with the questions regarding abbreviations because I just wasn’t expecting that. The MCQs were typical of a Lang exam, based on what I know from the practices I did in class. I guess Lang expects students to analyze a bit deeper than Lit. The essays for Lang are definitely tougher than for Lit because of that.
All that aside, congrats on your scores! You may have been disappointed with a 4 at first, but it won’t matter to you in the long run. Actually, it’s been a few months now and I doubt it matters to you that much anymore.