This might be a dumb question but i have been doing some research and cant find and exact awnser. My question is what (design & structure wise) makes a door speaker sound better than another one if the givin situations were all exactly the same. As in, for example, an Alpine Type S vs RE Audio XXX series.

Quality of components, crossovers, lots of stuff.

Thanks..look like i made an easy question hard

I know what you are wanting to know so hopefully it will come out right-

There isn't one speaker that will be "god", there are many.

What makes a speaker different from another, or better than another is how you perceive sound.

Different materials used to make the cones, different ways tweeters are made will effect it's sound output. Not everybody likes one particular speaker.

The specifics are what most brands tell you-

what type of enclosure, t/s parameters, x-over settings...

That info is so you can set it up properly to get the best sound from that part, but to make that part better than another has to do with the materials used.

research different types of materials for speaker building so you can decide what you might like the best then go to your local store and listen to speakers that you know use certain types of materials to get a general idea of the sound difference.