This model is the CH version with Swiss plug. This model Kärcher SC 5 EasyFix (4.20 Bar, 2250 W) is the EU version with a Schuko plug, a fixed adapter is included in the scope of delivery. There is no technical difference.

Please link me to the other version so that I can compare them 😊

Cleaning agent should not be poured in. I assume that the appliance will break if anything is poured in. However, cleaning agent is not necessary - it dissolves all dirt.