Hi SJ, my N500 came with both of those chargers too.
The charger cables terminate with a 1.7mm plug (I discovered) that plugs into one of two multipin adaptors that also came with the N500.
One adaptor is meant for car use and has no other connections. The other one is on a USB cable which has a sort of piggy-back socket, so that the charging current can be taken from the charger.
(Could be either charger, instead of the USB 5V supply. But I never use any USB devices such as a laptop in the car. USB current is rather limited, especially if you already have a hub dividing it up.)
I thought one advantage of my replacement plug would be that it has a 90-degree elbow, so does not stick out so far below the N500 across the car dash.