'Than' is only used in comparisons. Ex: You are bigger than me. Today is hotter than yesterday. 'Then' can be used to indicate that something happened/will happen after something else. Ex: I will go into the garage. Then I will get into the car. I got into bed and then fell asleep. 'Then' can also be used to make a conversation flow better. Ex. "A: I'm hungry. B: Eat something then." "A: This is my house. B: Then you must be very rich." "If it rains, then we'll need an umbrella." "Then eat something" or "You must be rich then" are also possible.

"Then" its like "dann" in German. So you usually say "than" to show you want to do something after somthing else or the time line. For example: I want to go to home and then do my homework. Or. You should call your mom first and then come over. But "than" its like. "Als" in german when you want to compare. For Example : I prefer to go home than staying here. Or. I want to play a game more than doing my homework. "Than" always come with preferences

then means that time, than was used to compare two things