Build up and Make a mountain out of a molehill

Build up verb - To become greater in extent, volume, amount, or number.

Make a mountain out of a molehill and build up are semantically related. In some cases you can use "Make a mountain out of a molehill" instead a verb "Build up".

Build up and make a mountain out of a molehill are semantically related. Sometimes you can use "Build up" instead a verb phrase "Make a mountain out of a molehill".