I’ve once wrongly reassembled the kornie keg outposts after a clean, and it’s most annoying!   I could not find much useful information about identifying them, so here it is:

On the left is the outpost.  That’s where the grey disconnects go.  It goes with the shorter pipe inside and is generally used for the CO2 pressure.

On the right is the inpost.  That’s where the black disconnects go.  This one is connected to the long pipe, reaching all to the bottom (in my case almost to the bottom since I shortened them to avoid sucking up yeast and other unwanted material).  Usually this is used for dispensing the liquid.

Now, they are awfully similar, except for the ridge that is etched on the sides of the nut for the inpost.  All of them are like that and it’s quite handy because one can easily feel which one is which under conditions which poor light.

And that’s it!  That’s all there is to know 🙂