I did my Masters at Fudan and I felt like the quality between exchange students and native students was extremely clear.

Also for reference back then, 3/4 of the 'international' students were actually just Chinese students with a foreign passport. I don't know if changes have been made to this kind of application or not, but it was definitely very common for wealthy Chinese students with mediocre grades to apply via a foreign passport.

International full-time students tended to be ok. Generally not the brightest minds in the world but not bad (There were a couple of extremely intelligent people in my program but they went back to Europe and stuck to academia, not industry). Non-degree exchange-students were absolutely horrible. They tended to come on 1 semester exchange programs, live in a flat with 10 other broke exchange students and get wasted everyday. All the worst stereotypes about expats you can think of rolled to 10.

I would say the graduation rate or difficulty was universal across the board though, at least it was in my program. The dropout rate was MASSIVE. My program started out with a massive class and on my thesis defense date we were like 5-6 maybe.