ssh : diff login account, but same name@host.. why ?

I am learning ssh on KDE to remote ssh server.

I logged into a same remote shell using same local machine, but with 2 different shell account that i have made.
What confused me is that, both login are same name ? How come same login name ? displayed on # prompt of terminal ?

Code:root@Roc:/# w
20:07:50 up 1 day, 13:28, 2 users, load average: 0.00, 0.00, 0.00
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
root pts/0 32.221.190.15 19:49 10:54 0.08s 0.08s -bash
User1 pts/1 32.221.190.15 19:37 0.00s 0.06s 0.00s w

root@Roc:~# cat /etc/passwd
root:x:0:0:root:/root:/bin/bash
user1:x:0:0::/home/user1:/bin/bash
Code:login 1:
---------
***(login as : root)***
root@Roc:/# whoami
root

root@Roc:~# cd
root@Roc:~#Code:login 2:
--------
***login as : user1 (with root privilege)***
root@Roc:~# whoami
root

root@Roc:/# cd
-bash: cd: /home/user1: No such file or directory