Both quantities are about different properties. The 0.1 Ohm number is about signal loss when a (lengty) cable has too much resistence. The second cable seems to be meant for 6 ohm speakers, which I think is a bit of a doubtful characteristic (as impedance varies greatly over a frequency range, in a very speaker-dependant way).
Assuming the cable you have is the 6mm variant, for any reasonable length it will almost certainly have an impedance of less than 0.1 ohm (most 6mm speaker cable has an impedance of about 3 ohm per km which means a 10m run will be about 0.03 ohm)
Impedance (as opposed to resistance) of the cable is only important when the cable is of the order of the wavelength of the varying signals. These travel close to the speed of light. So if your cable is shorter than 100 meters, and your frequency is less than 1Mhz, the impedance doesn't really matter.