良い is just the kanji for いい. It can also be read よい, which is more formal/literary/written style. The distinction is hardly worth worrying about at your current level. You could use hiragana いい for everything and no one will bat an eyelash.
I don't worry. I'm just keen. That is not the attitude I have when learning is concerned. If both are taught at the elementary level, then they must be important at this level, I wouldn't willy-nilly use the words if I can help it.