What is the different between Heavy 4x4 Tanker and Water Carriers? (UK)

You asked this in the US forum, but mentioned UK in the subject line.

Please confirm, is this for the UK version?

Thank you,

Quote from andrew143paz

Both got same Max Crew 3, and Pump capacity at 2000 l/min? Does anyone know the different?

Heavy 4x4 Tanker counts as a Pump aswell as a Water Carrier