difference between passwd and ldappasswd?

[Hardi Gunawan <hardigunawan@inbox.lv>]

I've just realized that there's a big difference between passwd and ldappasswd 
(or am I wrong?)

I'm using Redhat 7.3 with authentication from LDAP.  When I do a getent 
passwd, the user's entries are different:

testone:5a$cXdwML3j$Gm97On43TqRsd/eZ/qwrk.:501:501:testtwo:/home/testtwo:/bin/bash
testtwo:x:502:502:testtwo:/home/testtwo:/bin/bash

When I change the user testtwo's password with ldappasswd, the entry remains 
the same.  But when I change using passwd (passwd recognized that the entries 
are in LDAP) the result will be as testone.

But still, using both method, I'm unable to "su" to another user (with 
incorrect password error), unless I'm root (which doesn't require password).  
So I guess there's some steps that I did wrongly.  But one thing that puzzles 
me is that, a telnet to localhost and login as another user is ok.  So I'm 
confused whether the problem is the password, or the /etc/pam.d/su.

Can anyone help?