While both of the bulbs you posted pics of have the same base, the one on the right is the type you want. The one of the left is typically a standard bulb that's used for outside lighting and is usually not the right color temp (K
rating) for aquarium use. The rounder bulbs are usually in the 4000K-5000K range. You want a bulb that's more around the 15000K range and they are typically elongated in shape like the bulb on the right.