Philodendron Mamei and Silver Cloud are different plants of the same species that are almost identical and hard to differentiate unless you put them side by side. Silver Cloud is probably a Mamei hybrid, but I could be wrong. The main difference is the leaf shape, amount of silver variegation & the ridges.Philodendron Mamei has elongated heart-shaped pointier leaves, while silver cloud has more rounded heart-shaped leaves. The second difference is the colour of new growth, so in Philodendron Silver Cloud the cataphylls are white while for Philodendron Mamei they are red.