exercise和sport有何不同？

康軒一下
第五課對話中談到一位體育老師
"But she is very energetic. She likes exercise..."
一位一向很會發問的學生來問我，
exercise和sport有何不同？ 

要區別exercise和sport有何不同？
最好的方法當然是查英英字典，因為兩個字中文意思都是「運動 」。
Longman Dictionary of American English的定義:
exercise: physical activity that you do regularly in order to stay strong and healthy.
(以健身為主的運動)
sport: physical activity in which people compete against each other, and that has rules.
(有競賽性質的運動)