I’m studying Arabic with lingq these days, and was quite happy yesterday when i got a message telling me that I am now in advanced 1 because I know 12500 words. I think that arabic is much closer to russian, though with it’s amount of vocabulary and the inflections of the words. In Arabic you can say a whole sentence with just one “word”.
I did a comparison between french, arabic and russian with a unique word counter, using some texts from the united nations website, and found that arabic and russian have roughly 53-55% unique words while french has about 35%. I wasn’t able to find very long texts to compare. The ones i compared had roughly 1000-2000 words, so it might not be very reliable, but the result was about the same throughout three articles.
Anyway, I know that Arabic is just a beta language on this site, but I just wanted to point out what i found, if you’d like the proficiency levels to be more precise