food remaining after a meal. (吃完飯後,剩餘的食物)
例句: This recipe can serve four easily, and the leftovers are just as good eaten cold.
small bits of food which have not been eaten and which are usually thrown away.
例句：We give all our scraps to our cat.
Basically, they're the same. 不過,要指"吃剩的",用leftovers較好哦 ^.^
You can use them in your writing. (For words changing.)