What does "It makes all the difference in the world." mean?

Question

What does  "It makes all the difference in the world." mean?

Answer

it makes a big difference = it makes a world of difference

Answer

make all the difference in the world = to have an important effect and  make a very big difference. Example:  Our football  team has a fantastic coach, and that makes all the difference in the world whether we win the grand final or not.

Answer

make all the difference (in the world)
to have an important effect make a world of difference

example
Our team has a fine coach, and that makes all the difference.