File block system

Hello

I have a SSD and USB drives.

1.
Is the the file block system on those the same as on an HDD?

2.
Can a block hold parts of two different files?
File A – block 1 2 3 4
File B – block 4 5 6 7

3.
Which scenarios will relocate / move data from a block to another?
Drive optimize / defragment?
Delete file (Windows marks the block as “free”), and then the block get overwritten by new data later?

Thank you