Question about SanDisk Ultra 3D

Read/write rate of the Sandisk is a little faster, but Max. Random 4K Read/Write are higher on the Samsung.
In everyday use you won't notice a tangible difference just because the values are so close to each other, it only becomes noticeably faster/slower in benchmarks.

You won't notice the difference.
Depending on the measurement method, the Sandisk is sometimes faster and sometimes slower.