I've downloaded Forge 6.6.0, supposedly for Minecraft 1.4.7, but some mods are complaining about the Forge version being too old even though they are also 1.4.7. I've received a suggestion in chat that says:

A bit late, but in case you haven't found out why that is. You've downloaded Forge (the API that makes creating mods easier) 6.6.0, ForgeModLoader 4.7.whatever is the thing that takes all the individual zip files that mods come in and loads them for you (and various complicated stuff to make sure it all works).

So what exactly am I supposed to do? Is there a difference between the Forge API and the ForgeModLoader? If so, how do I differentiate between the two and install the correct FML?