Build up and Run up

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

Run up and build up are semantically related In some cases you can use "Run up" instead a verb "Build up".

Run up verb - Pile up (debts or scores).

Build up and run up are semantically related in adjoin topic. You can use "Build up" instead a verb "Run up", if it concerns topics such as accumulate, improve, increase, enlarge.