What’s the difference between the scientific study of psychology and having a general interest in human behavior? does it really matter?

I don't see much of a difference, besides the fact that psychologists will typically have gone to college to study human behaviour, as well as make a career out of this study, while people with a general interest will stick to personal research and personal experiments.

It might become confusing when you have someone who has gone to college for psychology and does not have a career, but rather just an interest, or someone who has a career but no college research. It really doesn't matter, depending on how you look at it.

I'm not sure if this is the answer you were looking for, but I hope this helps! <3