M.2 SATA NVMe onboard vs M.2 SATA NVMe on PCie card

Hello,

Is there a difference in performance if one were to use the same M.2 SATA NVMe drive on board vs using a PCIe expansion card? I imagine there would be but not sure how significant it would be. I was wondering because i got a new drive and want to set it up on my PC and use it for gaming. I already have a M.2 slot taken on the motherboard and would like to just use a expansion card but favor performance if its worth it and will make a switch.

Does anyone know what differences in performance and function between onboard vs PCIe expansion? Does it depend on the PCIe card's specs that you use?

Thanks for the help.