you use "than" to compare. for example, "my house is bigger THAN yours." Then is used when you are sequencing something (Then, the dog barked) or when you are talking about the past (I used to be...
If the question is how do you remember which one is which, here are two possible methods:
1. The height of the symbol is smaller at the pointy end than it is at the "open" end. So the smaller,...