What's the difference between Ti-89 and Ti-92 graphing calculators?

[Math100]

TL;DR

What's the ultimate/huge difference between a Ti-89 (Titanium) and a Ti-92 Plus graphing calculators? Which graphing calculator is better for a student who studies advanced mathematics?

Currently, I own a Ti-89 (Titanium) graphing calculator but it doesn't seem to work, I've replaced new batteries and it still doesn't work because the screen is still blank after I pressed the 'On' button. I used this graphing calculator for more than 10 years and I think I should just buy/purchase a new one instead of fixing it, although I'm not sure if this can be fixed. My question is, should I get another (same) Ti-89 (Titanium) graphing calculator again or buy/purchase a Ti-92 plus graphing calculator? What's the ultimate/huge difference between these two graphing calculators? Which one is better and more suitable for a student like me who studies advanced mathematics? Right now, I study "Nonlinear Ordinary Differential Equations" and don't know if Ti-92 Plus will be a better choice for me. In terms of thinking/planning for the near future, should I get the Ti-92 Plus instead?

 

[Drakkith]

Per wiki: https://en.wikipedia.org/wiki/TI-89_series

The TI-89 is essentially a TI-92 Plus with a limited keyboard and smaller screen. It was created partially in response to the fact that while calculators are allowed on many standardized tests, the TI-92 was not due to the QWERTY layout of its keyboard. Additionally, some people found the TI-92 unwieldy and overly large. The TI-89 is significantly smaller—about the same size as most other graphing calculators.

The TI-92 appears to be pretty large and not usable on many standardized tests. The TI-89 Titanium appears to have slightly better specs. Personally I'd stick with the TI-89 Titanium due to its smaller size, apparently equal capability, and slightly better specs.

 

[Vanadium 50]

The 92 is an 89 in a bigger box and with a alphabetic keyboard.

 

[Math100]

Thank you so much, guys! Now I know what I want!

 

[Vanadium 50]

One other thing to look at - batteries/battery life. May be different too.