No, that’s not really that significant. The ryzan 3d variants have 3-4x that much, then it’s significant.
The i9 is better in everyway, cache (only slightly though), cores (doesn’t rally matter for MSFS), turbo (can also overclock the i7 to same turbo as i9 if needed). The only question is if it’s worth it the price increase. What GPU do you have an what resolution do you play at? My hunch is unless you play at 1080p with a high end GPU you will get near identical performance with the two CPUs, so may wanna save your money.