Is there a massive difference between M3 Pro and M4 Pro (base models)?

Yes almost 40% diff in performance, and ofc more RAM.

Should have waited, now you can wait for M5, it will be a redesign. /s

Disclaimer: This is not meant rude.

If you have to ask this question:

There is no difference for you.

Simply because most differences that will make a change in certain tasks are so special, that you would know immediately. Mainly the biggest plus will be the bandwidth of the CPU/GPU. The M3 Pro had ~150 GB/s, the M4 Pro ~270 GB/s. So nearly double the speed. In pretty much any everyday use case you wont notice the difference. But for special tasks like running a local LLM it is a huge step, since the bandwidth is one bottleneck on running local AI (beside RAM). Nevertheless if you need local LLM you should rather use a M4 max (540 GB/s bandwidth).

All the changes are pretty much on this level (eg video editing, science simulations and so on). It might get interesting for gaming. But to be honest, if you do regular office works and want gaming, you can invest the same amount of money into a Macbook Air + Gaming PC and you will be MUCH happier.

I’m in the same boat as you are. I bought the M3 Pro 18 days ago and I can’t return it to upgrade it 😭🤣

Same here man.