Your role is insanely important in league, and don't you forget it.
It dictates how you play, what you build, and your experience. For example, I'm a support main. I enjoy it, but sometimes I feel like playing another role. But I struggle with it, mostly due to the fact that many supportive habits are ingrained deeply in me. It's difficult to take the gold from minions because of the fact that I play support and am therefore usually supposed to do whatever I can not to while my laner is there.

Top lane and mid lane are the powerhouses, usually with the most amount of levels. They get exp all to themselves due to the fact that they are alone in lane, and get gold from minions. Mid is more likely to get ganked(attacked by jungler) compared to other lanes because they are always next to you if in the jungle.

You roam the jungle, killing camps and attacking lanes when the opportunity comes up. Some champions may not be able to gank early game, as some may be great at it early.

Bottom mostly acts like mid lane and top, but are usually lower in level because they have to share exp with the support. The support, as the name may inform you, supports the bottom laner.