"To" is a preposition that introduces a noun. Go to the bank. "Too" is an adjective . Can be used to express A greater amount . Too much, too close
'To' is used when you give directions: "Then you go to the roundabout!" 'Too' can be used instead of 'also': "Are you coming, too?" Or it can be used to describe a large amount of something: "There are too many coins!"