Whats the difference between a speaker and a subwoofer

a passive subwoofer is just like a regular speaker that gets it's amplification from you receiver. An active subwoofer has it's own built-in amplifier

If the sub doesn't appear to have any damage like broken surround or a torn spider then I would suspect the amp may be having problems. What impedance are the speakers, what impedance can the amp handle, how do you have it wired to the amp?

You blew the amp. If you were running 4 subwoofers off of a dual channel amp you most likely running them bridged off of two different outputs. You most likely blew the resistor and because it was pushing more power then it could handle. Also when you bridge speakers it brings down the impedance which allows for the more power to course through. Suggestion is to buy a new amp that can handle 4 subs or 2 different amps for both sets.

running subs with speakers is not a good idea bcs of the different frequencys of them but parrellel wiring is best prolly
+ to + and - to -

We used to use what we call bass blocker capacitors on the component speakers to block the bass coming from the head unit and to allow the bass to only come from the subs...there is several values of these capacitors that you can use(different values correlate to different frequencies). These type of capacitors are available at Radio Shack. You will need to request a NON-POLARIZED Electrolytic capacitor at a voltage rating of not less than 25 Volts...As for the value of the microfarad rating..you may need to experiment with different microfarad values to get the sound you desire...standard microfarad values are 1uF, 2.2uF, 3.3uF, 4.7uF, 10uF, 22 uF, 33uF, 47uF.
You probably won't need to go any higher on the value than those listed....in my experience, I have found the 4.7uF and 10uF to be good for most speakers...to install these...you need to put one inline with the positive lead to each component speaker.

i seen some on ebay with different specs

off the same amp? you have two way different sounding speakers man. you can buy 2 identical speakers from the same company and brand and series and they will play differently every time. you have 2 speakers with nothing in common so you will hear a difference and maybe interference because of the different ohm levels.

Hiya by rattling i am assuming like something loose/fell off etc (rattling sound or distortion on the speaker itself is different, speaker could be damaged or braiding damaged that 'Might" make the speaker come in and out.) Something could have come of the PC board and may not be to serious. Probably protecting as not 100%. It may be as simple as resoldering the part but if not sure on your side i would advise seeking some help. Best of luck

just try leaving it unplugged for a while thats what i did and it fixed it

did you tell the receiver that you have a subwoofer connected (thru the quick setup)?