Part of this comes down to differing definitions, others down to differing sources. The British casualties are a prime example of this. The German article does not provide a breakdown into dead, wounded and captured, instead giving only the total number of casualties, 68,000. Meanwhile the English one gives numbers for dead and captured, but not for wounded. This explains part of the discrepancy. For troop and materiel losses (artillery pieces and vehicle losses), the numbers in the German article are identical those given in Chapter 23 of the British Official History for the Battle of France. However, these numbers are not for Dunkirk alone. Instead, they cover losses for the entire campaign in France and Flanders, including fighting before and after Dunkirk. This explains the remaining discrepancy between the two sets of figures - the English article is only giving losses sustained in the Battle of Dunkirk itself. For aviation losses, the difference between the two articles lies solely in the sourcing. Both sides made hugely inaccurate claims about how many aircraft they shot down, so a source that relies primarily on German records is going to give a very different picture from one that relies primarily on British records.

The German article also uses a wider definition of the battle than the English one does - it includes things like the battle for Lille. While this battle had a major impact on the evacuation by delaying the German advance, it is not, by itself, considered part of the Dunkirk battle in English scholarship. This wider definition accounts for part of the difference in Allied strengths between the two articles - 1.2 million in the German article, compared to 400,000 in the English. The remainder is because the German article includes the ~500,000 troops of the Belgian army. These surrendered at midnight on the night of the 27-28th May 1940, and so played little part in the development of the battle. The German article also only lists the major militaries that took part in the battle - while Polish, Dutch and Canadian troops, pilots and sailors did take part in the Battle of Dunkirk, they did so under British or French command. The Polish destroyer Blyskawica took part in the evacuation, but was under RN orders, and was well integrated into the British command structure. Dutch participation included 40 schuyts, small motor coasters, which proved to be highly useful to the RN shuttling troops between the beaches and the larger ships waiting offshore - again, these ships, while Dutch-manned, mostly operated directly under RN command.

Also the german one tells of 68,000 dead brits, whereas the english pages tells of 11,000.

Correction: the German statistic says "68.111 Gefallene, Verwundete und Gefangene", i.e. "dead, wounded and captured", which could fit pretty well with the numbers from the English wikipedia.

As for the vast differences in the total numbers, my guess would be that one version also takes the civilian population into account.

But you should probably wait for an actual qualified answer for that and the rest.