Yes, the # symbol denotes a comment from that point to the end of line. I use a pair of them just for better visual separation.

Assuming the "boot information" is in the first partition of the old drive, the above method will clone that to the SSD as well as the main partition. No extra steps required.

Just be sure and get the drive names correct, and the right way around. gparted shows the names ("sda", "sdb", ..), as does the (often missing) lsscsi command. sudo (aka. SuperUser DO) is merely a "prefix" that says to run a command (after the "sudo" part) as the superuser, with full "admin" privileges for direct hardware (disk) access.

The actual command ("cat") will eventually "fail" with a message of some kind about running out of space, but that can be ignored for this specific usage. Do, however, add a "sync" command afterward. I left that out originally.

Cheers