Colombovac is a water based vaccine. Nobivac is an oil based vaccine. They are both used in the same manner by vaccinating under the skin, but whilst care must be taken with both, the oil based carrier in Nobivac can cause more serious problems if accidently vaccinating yourself. Nobivac is a thicker liquid than Colombovac and as such can be a little more difficult to use, but seemingly better results are achieved with Nobivac. I think this comes down to fancier preference although I do use Nobivac myself.