Excuse me, are tiger-spotted Siam and key-colored Siam purebred cats?

Siamese cats come in many colors, such as seal, blue, chocolate, light purple, red, cream and so on, as well as various striped key colors. The so-called tiger-spotted Siam belongs to one of various stripes. Some organizations will also have independent varieties of short-haired cats. So generally speaking, the two kinds of Siam you mentioned belong to purebred cats. For specific standards, see the organization standards of purebred cats in various countries.