Subtraction
Subtraction is one of the four basic arithmetic operations. (The other basic operations are addition, multiplication, and division.)
It helps us find answers to questions such as the following:
How many are left? or How much is left?
How many more (or fewer) are there? or How much more (or less) is there?
How many more are needed? or How much more is needed?
Remainder
In the context of subtraction problems, a remainder is the number left after something is subtracted or "taken away." It is more or less the same as a "difference," which is addressed later.
Example  

Difference
In some subtraction problems we need to compare two numbers to find out how much larger or smaller a number is compared to another. The answer is called a difference.
Example  

Missing addend
Subtraction is one way to find a missing addend, or how many more of something must be added to have the desired number.
Example  

See also difference, missing addend, operation, remainder.
Related words subtract