Command line expansion:

Tilde command: (~):

May for your user home directory:

$ ~ cat /.bash_profile

.bash_profile is own user's home directory.

may its refer for another user home directory.

$  ls ~nandhini/.public_html

.public_html  = Its refer for another user's  home directory.

When the tilde command is used, whether  the command is referring for your own's home directory.