[CentOS] adduser vs. useradd

Hi,

To add a user to the system on the commandline, I usually use the 
adduser command.

# adduser newuser

And that's it. I've been using that command probably out of an old 
habit, since I've been a long-time Slackware user before. But now I 
wanted to dig a bit deeper, and some details puzzle me.

Whereas on Slackware, 'adduser' is an interactive shell script to create 
a user so that basically you don't have to memorize all the 'useradd' 
switches, CentOS' 'adduser' is a mere symbolic link to 'useradd'.

But when I add a new user (# adduser newuser), I don't use any switches, 
say to specify the shell, the home directory, the password expiration 
delay, etcetera. I understand that it is Red Hat (CentOS) tradition to 
create a separate group for each user. For example, user kikinovak also 
belongs to a group kikinovak. And when I create a new user 'newuser', 
the 'newuser' group also got somehow created. Plus, the new user also 
seems to have his own user profile, with a default .bashrc and so on. My 
only explanation for that is that CentOS' 'useradd' command doesn't work 
like the traditional UNIX useradd command and uses a few switches by 
default. Please correct me if I'm wrong.

Any light on this?

Niki