Gaming PC does not perform well in e.g. Fortnite?

I hope so. Can help me or explain the logic behind it to me.
My PC: GPU: rx 5700 xt
CPU: Ryzen 7 2700X
RAM: Trident Z RGB 32GB 3000mhz
Mainboard: Asus ROG Crosshair VII Wi-Fi
Power supply: Dark Power Pro 11 platinum
SSD: Samsung EVO 960 1tb
Buddy PC: CPU: Ryzen 5 1600
GPU: Gtx 1080
RAM: 16gb gskill 3200mhz
Mainboard: asus prime b350 plus
Power supply: dark power 8 600w
Storage: 240Gb ssd 500gb hdd 3tb hdd
It has a constant 144FPS in public and my PC can't handle it, which in my opinion doesn't make sense. According to AMD, I have an average of 139FPS and my PC is significantly better than his.
My settings are all ingame on low.

An uproar because of 5 FPS difference? You don't even notice them in the slightest.

Ehmm but that my PC is much better makes no difference?