Here is a better version of the table you are looking at:
http://www.quarry.nildram.co.uk/WW2guneffect.htm
The MG151/20 used the 20x82mm round, where as the HSII, HSV uses the 200x110m.
If I'm understanding the history of the guns right, The MG151/20 round was developed from a combination of the MG FF and MG151/15 round. The MG FF was an outgrowth of the small Oerlikon FF cannon. The HS.404, which developed in the HS MkII and MkV used by the British, was developed from the heavy Oerlikon FF S line of cannon.
Basically, between the wars Oerlikon developed the MG FF action, and made three sizes of gun with it, the Oerlikon FF, the FFL, and the FFS. The German MG151/20 fires rounds based off of the smallest of the set, while the British gun is based off of the biggest gun of the set. The US tried to adopt a belt fed version as, first the M1, then M2, and finally the M3, but it never worked very well until they reached the M24 version. The Japanese adopted the FF as the Type 99-1, and the FFL as the Type 99-2.
I think about the only group (aside from the US, and only because we couldn't get it to work) that wasn't using some variant Oerlikon, were the Russians, who were using the ShVAK, which was, perhaps, the first revolver cannon. It would be rather interesting to see just how closely the Mauser MG 213 happens to be related to the ShVAK mechanism.
Harry Voyager