Runup and Running start

Runup noun - A substantial increase over a relatively short period of time.

Running start and runup are semantically related. In some cases you can use "Running start" instead a noun "Runup".

Running start noun - A racing start in which the contestants are already in full motion when they pass the starting line.

Runup and running start are semantically related. Sometimes you can replace term "Runup" with "Running start", this terms are similar.