This is because finder uses MB/GB rather than MiB/GiB. For any reasonable person a MB is 1024 KB which is 1024 B however some non-technical people decided this does not fit with base 10 scientific notation and they somehow convinced the rest of the world that a MB is 1000 KB which is 1000 B.
`ls` reports files in KiB, MiB, GiB, etc. Although there is no need to designate them as such because those things existing is pointless.
/end rant (°°
If we do some conversions though we can see that the sizes match up (or at least are close):
7.6GiB -> 8.16GB
1.8MiB -> 1.887MB
1.9MiB -> 1.992MB
Related: OS X Finder not showing correct file size - why and how “fix” it?