Milgrom has succinctly summarized the various opinions. Huqat The purifying effects of the red cow described in Numbers 19, resembles the rites of the purification of the leper. Both of these rites are executed outside the camp. Both involve the use of blood, water, cedar and hyssop, and crimson-dyed wool. Both achieve their purification after seven days.
Differences are also apparent.
For the purification of the leper two birds are used, as opposed to the cow used in the purification from corpse contamination. Another major difference is that the leper must bring a sacrifice on the eighth day whereas this is not necessary for the one defiled by a corpse. In addition, in the red cow rites, everyone involved in the preparation of the ashes and the purification becomes impure for one day, this does not occur in the leper purification. It is this last difference which has led the sages to say that this law was incomprehensible even to Solomon, the wisest of men. It is reasonable, therefore, that the purification from these defilements should be similar.