When there is a sufficiently strong link between the products for them to be considered complementary, they can belong to the same market despite their differences. Such is the case for the markets for the collection and sorting of used sales packaging for private consumers, insofar as the two services are inseparable, despite the fact that each service requires a different infrastructure.

Nevertheless, competition authorities generally tend to distinguish as many markets as there are products, even when the products are intended to meet the same needs. So, the fact that liquid food products require their own methods of packaging and machinery, that vaccinations are meant for different uses, that ice cream retail requires possession of a freezer provided free-of-charge by the supplier, is enough to identify distinct product markets. Likewise, despite the card issuing activity belonging to the two-sided payment systems market, issuing and acquiring services differ and target distinct customer-bases as effectively, on a two-sided market, one of the sides may be the relevant market and the other a separate related market with the interaction between them constituting only a contextual element to be taken into consideration for the analysis of the anticompetitive effects on the relevant market. Likewise, the Commission may not decide that the luxury and prestige watch market and the market for their spare parts are the same market without showing that a moderate increase in the price of spare parts by a specific producer would lead the demand to switch to other watch producers and render such an increase unprofitable.