The only to differences between the models is that the Professional has a larger volume boiler, and comes with a pressure gauge. The Europiccola is smaller and has no gauge (which is not an option to add/retro-fit). In order to tell which edition La Pavoni you have, and you do not know and cannot find the manufacture date, you will need to remove the lower base and look inside for a sticker that says "Millennium". If no sticker exists, it is a "pre-Millennium" edition, meaning it was manufactured before August of the year 2000. Unfortunately, this is not fail-safe way to tell, of course, as the sticker could have been lost or they neglected to put one on.
Another way to check is to measure your baskets. The Millennium editions have a larger portafilter basket. These accept a 51mm diameter tamper base. The older version portafilter baskets accept a 49mm tamper base so they are very close in size. You can also check the measurements of your portafilter, in the event you've lost the basket and cannot measure it. The Millennium edition portafilter bodies measure 54mm on the inside diameter. The older version portafilter bodies measure 52mm on the inside diameter. The MP (for Millennium Pavoni) 68 and MP69 baskets are for the Millennium edition, and the P68 and P69 baskets are for the older versions.
You can confirm your edition another way. The older versions do not have a black plastic insert behind the group head. By removing the group head, you can inspect it for this insert. You will want to have an o-ring (P45) on hand first to reseal the group in case the o-ring tears or won't re-seal.