There is a wattage difference between the 36v 1212 and the 50v 1812. If your driver is 700ma you would multiply .7x36 for the 1212, or .7x50 for the 1812.
The 1212 will give you 25watts and the 1812 will give you 35 watts.
The 1212 will give you 25watts and the 1812 will give you 35 watts.