What does "small change" mean?

[Svetlankaj]

Test No. errors/inter-6 "The worse it will be", question 8

I need to make a phone call but unfortunately I only have notes so could you let me have some small money.

(a) to make
(b) unfortunately
(c) notes
(d) money

Test No. errors/inter-6 "The worse it will be", answer 8

I need to make a phone call but unfortunately I only have notes so could you let me have some small change.

Correct entry: change
The error was: (d) money

You have found the error but your entry is incorrect.
I need to make a phone call but unfortunately I only have notes so could you let me have some small coins.
_________________________

Why I can not used the coins in this sentence? What is the difference between change and coin?

[Torsten]

Hi,

We say small change when we mean a small amount of money which are usually coins. When you want to make a phone call you can insert big coins as well as small ones.

TOEIC listening, photographs: Canoeing