Good PC hardware, not so good fps?

I hope someone can help me understand my pc.

In Fortnite I have the problem that I get a static 240 fps in creative mode, but only 120 fps in the normal rounds… But with a little research I found out that my hardware is the same / partially better than the pro's who use it online Play 240 fps…

My hardware looks like this:

Processor: AMD Ryzen 5 2600X with 6 cores

RAM: 16 GB RAM

Graphics card: NVIDIA GeForce RTX 2060 great

I would also like to note that I already use optimal in-game settings (optimized by geforce experience for performance), have deactivated all energy-saving modes and no background applications suck up performance.

The difference is that in creative mode you are alone or just with a few friends. There are already 100 players online.

Because of the other players