From the equipment life and reliability perspective there is no difference. From the heat transfer performance there is but since this coil is relatively small and the coolant flow available relatively great you probably will not notice the difference.

From the design point of view for heat transfer coils the preferred flow would be for the source medium (coolant) to counterflow the medium being heated or cooled. In other words you want the coolant entering the heat exchanger on the side the coolant is leaving. This arrangement provides the greatest temperature rise. There are situations where this is not done for example, heating systems taking in air at freezing temperatures in systems not using antifreeze. Especially if the coolant is throttled for control. The objective there is to prevent the coil from freezing.

Dennis