Longboards are shaped like a banana and they flex a lot when you ride them. The middle is bouncy. They normally have larger wheels. They are used for transportation and not for tricks.
A normal skateboard looks like this.. That is actually the one I was using until a few days ago. I normally use 95a (softness) 59mm (diameter) wheels. They are about medium sized and a little soft. I keep my trucks really tight so I don’t need to worry about the wheels hitting the deck.
A normal skateboard is going to be used for transportation and tricks. My knees are giving out so mine is mostly for transportation. But I will nollie up a curb if I see one. But on my skateboard I can get to the beer store in 2 minutes compared to walking ten minutes.
Most people that ride a normal skateboard loath people on longboards. I hate the damn things.