Cisco has weird naming conventions for groups of interfaces

If you want to bind some ethernet interfaces into one logical interface between two ciscos switches you have to configure an interface first:

interface Port-channel 1

then add some interfaces into this new interface:

interface GigabitEthernet 1/0/1
        channel-group 1 mode active

and you can check the status with:

show etherchannel 1 summary

Three names for the same thing. Does anybody know, why ?