The differences in the larger globed, wedge mount bulbs like the 906, 912, or 922 bulbs are mostly wattage, I've seen a lot of bulb housings and lenses melted by someone using a higher wattage bulb. Be sure to match the bulb with what it calls for. I also usually replace both even if only one is out, the other isn't usually to far behind.
The link below will give you specific wattages and other info for each type of bulb. (www.bulbs.com
I don't have a book in front of me here, but I believe that the third brake light bulbs should be a pair of 912 bulbs, and the cargo lamp bulbs are usually 906's if so equipped. These look identical, so be careful not to confuse the two if your changing both. Most interior lights also use the 906 version. The 912 is a 12.8 watt bulb. The 906 is only 9.3 watts, so its also much cooler when lit. The 922 is a 12.5 watt bulb, but is slightly smaller than the 912. Which would make it a safer choice in tight fixtures. Ford lists this for many newer models for the 3rd brake light as well, (2005 and up I believe). The 922 would most likely would work in the older applications as well.