All of these 3 Karcher window vacuum versions come with the WV 50 cordless window vacuum cleaner PowerSqueegee, they are just different in the included accessories.
image from manufacturer
The WV50 comes with a 11 inch Suction Nozzle, Lithium ion battery, and Battery charger.
image from manufacturer
The WV50 Plus comes with the 11 inch Suction Nozzle, 1 x 20 ml Glass Cleaner Concentrate, Spray bottle with microfibre cloth, Lithium ion battery, and Battery charger
The spray bottle is designed to evenly spray cleaning solution on smooth surfaces.
image from manufacturer
The WV55 comes with the 11 inch Suction Nozzle, a narrower 6 inch Suction Nozzle, Lithium ion battery, and Battery charger
The 6 inch vacuum nozzle is for vacuuming smaller surfaces.
The Karcher window vacuum cleaner PowerSqueegee can help you clean flat surfaces, such as windows, tables and mirrors, faster with no streak.
It is poweded by lithium ion battery, running time is about 20 minutes per charge, charging takes approximately 120 minutes.