Kerberos (heimdal) questions

[TheSmallOne]

Hi,
actually I tried searching for a specific Kerberos-Forum in the net, but I couldn't find one, so I'll try here.
I'm new to Kerberos and I think I'm making progresses in understanding it.
There is one point though, I don't really understand, even after reading the man-pages and several other documentation.

I hope someone here can help me. The thing is: I don't really understand the differences between the following (heimdal) commands:
kadmin ext_keytab
ktutil add
ktutil get

All of them seem to be meant to add some keys to a keytab, but somehow the keytabs created by them differ greatly.
Can someone explain the difference in an easy to understand way?