I have been curious about the difference between these two for a few months now. I finally got to see a comparison. The results surprised me when you put them both at 1.5X Zoom.

https://youtu.be/rPEhKL-OsH4

I think one of the best tests I've seen on the A7iii re HD FF/Crop 4K FF/Crop etc has been this clip from

Sony a7iii clear image zoom test and crop mode test in 1080p vs 4k - YouTube

Fairly surprising in some respects.

Chris Young

That is very interesting bro. Although I dont think I ever shoot HD. I have tried a few times just to use 60 & 120 for slow motion but I wasn't a fan. Hoping A7sIII or whatever next Sony Cam comes has slow Motion in 4K.