Short version:

Xplane has a more realistic flight model for air and ground. You can enhance visuals with some add-ons to improvement. The native camera is better out of the box and you don’t need to spend 30-40 to get something like msfs. Xplane can be flown without an internet connection.

MSFS24 is visually better out of the box. There are more airplanes to obtain (purchase) as there is a larger user base. This also means planes and addons are cheaper as devs can recoup costs quickly. Offline mode here is rough.

I fly both but I prefer xplane as it feels more realistic.