You can test how Ubuntu works by making live USB installation media. Then boot from that USB drive without having to install it. If you like using that version of Linux, just install from the same media -- no need to reboot.
There have been some changes made in Ubuntu 20 desktop, so try both distros to see which you prefer
You also have the choice of installing alongside the existing Windows OS, or deleting the Windows partition and running just Linux. Both choices have their merits, but on a brand-new PC, I'd opt for a clean Ubuntu-only installation.
N.B. Before making any permanent installation, image the HDD so you can go back if a disaster occurs.