> I got into advanced math classes but it was my brother who got the 84+ (I had to settle for a 83+)

I had a TI-85 (maybe 86), unlike the entire rest of my school who had 83s.

There was a difference: when programming in TI-Basic, variable names on a TI-83 are limited to a single character. On the 85, you can make them longer.

But that was pretty much the only difference, and it will never come up if you're using the calculator for school-related reasons.

(For calculus, I had an 89. The differences are much more significant there.)

The TI-85 also didn't have a lot of the built-in statistical functions that the TI-83 had.

I also was the one person with a TI-85 in a school of 83s. But by the time I took the statistics class I knew enough BASIC to write my own programs to replicate the functionality that was missing.