Sometimes whole house fans are called attic fans. However, the whole house fan is an entirely different concept. Whole house fans draw air in through the windows of the house and blow hot house air out through the attic. Of course a whole house fan would never be used simultaneously with an air conditioner or if you have allergies.
Installing a whole house fan is difficult; requiring a carpenter to frame the ceiling opening and and electrician to properly hook-up the electrical switches. Plus you need enough air passage through the attic to the outside so you will most likely need to add more attic vents.
Which one should you get?
If you have an unfinished attic and use air conditioning, an attic fan is a necessity. You never want your attic to be 150 degrees, even when your not home, while your air conditioning is running, or even if you’re on vacation. That is why an attic fan is needed even if you already have a whole house fan because it provides more air passage from the whole house fan through the attic to the outside. You can only effectively use a whole house fan on summer evenings, spring days and in the fall when outside air temperatures are below 82 degrees and when it is not too humid.