• A hard link is a direct reference to a file via its inode. You can also only hardlink files and not directories.

• Symbolic links are essentially shortcuts that reference to a file instead of its inode value.

(The inode is a database that describes the file/directory attributes such as metadata and the physical location on the hard drive.)

Example:

 1touch test
 2
 3ln test test2
 4ln -s test test3
 5
 6ls -l
 7
 8# `2` in second column is the number of hard links
 9# -rw-r--r--    2 zjf  staff       0 Jul 28 23:54 test2
10
11# `l` in first column means it's a symbolic link
12# lrwxr-xr-x    1 zjf  staff       4 Jul 28 23:54 test3 -> test

See:

• Hard links and Symbolic links — A comparison | by Andrew | Medium