By description SUB word, it means the speaker must be able to handle bass tones below.
Bass speakers can use the speakers with her without a rubber edge cones.
Speaker Sub Woofer, using cones with rubber edges, so its more flexible movement of cones.
Performance of all speakers (tweeter, Middle, woofer or sub woofer) strongly depends on the source signal and Pre Amp and Power of his amps. So if not supported by all three of these factors, it will not produce a good tone (tone control).
Regarding his Ohm, 100%, depending on its output amps.
Like the amps in the car, the output is 4 ohms, while the home is generally 8 ohm amp, but there is also a distinguished 16 ohms. So adjust the speakers to the amplifier.