k-meta is potassium metabisulfate found in campden tablets or better in powder form. Potassium sorbate prevents the yeast from budding and increasing in number it does not kill them. if both are used at the same time the yeast can be stopped and eliminated. sorbate is required when you back sweeten a wine as the additional sugar or other sweetener added will cause the yeast to restart multiplying. K-meta is used to sanitize. it also is use to kill wild yeast in a grape fermentation. it is also a preservative in wine .
K meta (SO2, Sulphur) is to protect wine from the harmful affects of oxygen, bacteria, undesirable yeast and other microbes that could otherwise grow. Potassium Sorbate is to keep yeast cells from multiplying.