I think the main selling point of Arduino is the "batteries included" approach if you're not familiar with embedded programing. Personally I never use Arduino because of the weird header spacing (I get it's sort of a trademark at this point but it's just annoying to work with).
If you don't care about premade environments then yeah, it's mainly about which pins and embedded peripheral the board supports. Pin count is not everything, nobody wants to bitbang USB or even high-speed SPI. For instance I see that this teensy board supports up to 18 analog inputs when Arduino supports between 6 and 15 according to this: https://www.arduino.cc/reference/en/language/functions/analo...
Basically the choice of controller should be the last step in your design: first thing about your inputs and outputs, then find a controller with suitable I/O and processing power (and preferably with standard header spacing).
RPi is more like a mini-computer than a controller, it's a lot more powerful and comes with massively more overhead. You program something like a teensy on "bare metal" with only a very minimal runtime. On an RPi you'd typically run a full blown OS. That opens up many possibilities but it's also generally more expensive and more power hungry. If you just want to drive 5 GPIOs it's completely overkill.
If you don't care about premade environments then yeah, it's mainly about which pins and embedded peripheral the board supports. Pin count is not everything, nobody wants to bitbang USB or even high-speed SPI. For instance I see that this teensy board supports up to 18 analog inputs when Arduino supports between 6 and 15 according to this: https://www.arduino.cc/reference/en/language/functions/analo...
Basically the choice of controller should be the last step in your design: first thing about your inputs and outputs, then find a controller with suitable I/O and processing power (and preferably with standard header spacing).
RPi is more like a mini-computer than a controller, it's a lot more powerful and comes with massively more overhead. You program something like a teensy on "bare metal" with only a very minimal runtime. On an RPi you'd typically run a full blown OS. That opens up many possibilities but it's also generally more expensive and more power hungry. If you just want to drive 5 GPIOs it's completely overkill.