Everything in Cologne is somehow “Kölsch”, that is Cologne (kölsch, from German kölnisch). The local beer brand is Kölsch. The local language is also Kölsch. But here's the curious thing. If, for example, people from Bonn or from Düsseldorf who were about to drink Kölsch means Cologne beer, then Cologne means beer in general. Say, there is no other beer except Cologne.
They perceive their own speech on the same scale. Although from Cologne to Bonn it is only an hour by electric train, and the people there already have their own language - “Bönnsch”, is in some way similar to “Kölsch”, but completely different at the same time.
Kölsch is very different from other dialects of the Ripuar group to which it belongs. The Ripuar or “river” group of dialects is distributed along the Rhine, not only in Germany, but also in the Netherlands and Belgium. Kölsch has certain riparian features: the merging of word boundaries, the ingestion of unstressed vowels and entire syllables, the characteristic transformations of some vowels and consonants (Ovend instead of Abend (German evening), Rödsel instead of Rätsel (German mystery), etc.).
But first of all, significant lexical differences are evident both with neighboring dialects and with the literary German language. This is not just a change in the form of words like Engk instead of Ende (German end), but also some distant borrowings. For example, the Cologne word Bajasch is derived from the French bagage, which means both Gepäck (German luggage) and Verwandtschaft (German kinship, relatives). In a completely incomprehensible way, the French panse (French unclean belly, belly) was transformed into the Cologne Pänz (Cologne child, cf. Kind - German child).
Sometimes it seems that the peoplfe from Cologne deliberately distorted their speech to make it incomprehensible to others. And there is some truth in it! In the Middle Ages, Cologne developed as a center for inter-regional trade on the Rhine. Transshipment warehouses were located here, and the city had the so-called folding right (German: Stapelrecht), which allowed forcing foreign merchants to trade on their territory or to merge goods through it. In general, the city was rich in transit, turned into prosperity every thing that passed by, which made up the need for corporate speech, a kind of jargon, incomprehensible to outsiders - in order to outwit them with the Polovtsi. Later, during the Napoleonic invasion and subsequent Prussian rule, the “encrypted” Cologne became, so to speak, a language of resistance.
But do not think that the Cologne inhabitants are smarter. Even before the French invasion, local peasants “invented” their own speech - in order to prevent the townspeople from doing their business and to enjoy their own profit by trading in urban markets. Therefore, today, at least two Cologne distinctions are distinguished: urban and rural (Stadtkölsch, Landtkölsch). What is, you can’t take it away! Or, in Cologne, et es wie et es.