"THERE", "THEIR", and "THEY'RE"

"There" refers to a place. "Their" indicates possession. "They're" is a contraction for "they are." Ex.: There is a beautiful garden. Their house is nearby. They're going for a walk.

"ENSURE" and "INSURE"

"Ensure" means to guarantee or make certain. "Insure" refers to obtaining insurance coverage. Ex.: Please ensure the door is locked. We need to insure our new car.