Hi! I just took the TEAS today, so the memory of it is still fresh in my mind. I took the online practice test (A) and my version of the protored TEAS was done online. I found that the real test had somewhat similar questions as the online practice test had. I did notice, however, that while the practice test question topics were all covered in the ATI study guide, some of the questions I got from the proctored exam was a bit more thorough and covered more specific topics compared to the practice test as well as the study guide. So the one thing I can advise (which isn't much, to be honest) is to really study the science part, especially if it's been a while since you've taken your science courses. While it's not exactly impossible to ace, some questions are just plain tricky
And like what some of the people on allnurses have said, I also got a higher score in the proctored TEAS than what I got from the practice test--but I think that's only because when I took the practice test, I still hadn't reviewed a single thing (and I took my prerequisites eons ago), so it was basically just me and whatever stock knowledge I had left about the sciences. I did notice that if I averaged the two results I got from the same practice test (since you can take the practice test twice), the average scores I got for each part were mostly very near what my real scores were in the proctored TEAS.
Hope I helped, and good luck! As they say, the anticipation is the hardest part. Once you're there, you find it's not as bad as you expected it to be.