Recommended by Max Lake
"THEN" and "THAN"
"Then" relates to time. "Than" is used for comparison. Ex.: First, we'll have lunch, and then we'll go for a walk. He is more experienced than I am.
"DISCREET" and "DISCRETE"
"Discreet" means careful or unobtrusive. "Discrete" means separate or distinct. Ex.: She was discreet about her personal life. The project was divided into discrete tasks.