Difference between "belong to" and "belong in" [closed]

"Belong(s) to" is used to express the actual origin/relation of someone/something.

"Belong(s) in" is used to express that someone/something fits better in {......}, but in reality he/it is not from {......}.

Example: He belongs in the National football team with his speed and aggression but at present, he belongs to the struggling local team.

To me the phrase "I belong in this world" most likely fits with someone who was disillusioned with the way things were going, and is somehow finding a way to get on their feet again. Something like, "This place really is home" or "If I have to work here I may as well identify with something of the place" It may well describe that the person no longer feels out of place, or out of touch, with the surrounding environment. I hope you don't mind that this is quite a speculative interpretation.

The general meaning is essentially as @Fr0zenFyr described it, in that belonging to something is already having the bonds to it, and belonging in something is having a purpose or destiny in that environment, whether that be a team or workplace, or whatever else.

Another example: "He belongs to the local militia, but with his training he belongs in the national army." would be a way of stating that his membership in the local militia is existent, but that he should leave and go the national army.