The wattage is the light output rating of the bulb. The voltage and current draw should be the same.
The 9004, H5, and 9007 are all three different bulbs.
Sylvania has a website where they list their bulbs by car model:
According to them, your car calls for 9004's.
The main reason that the wattage is higher on these bulbs is because Cool Blue and Silver Star are coated Halogen bulbs. The coating does two things: Filters out the yellow from the Halogen to make it appear to be "whiter". And diminishes the amount of output from the bulb, so they have to increase the wattage to compensate for the diminished "brightness".
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