Can kittens from the same litter be a different breed from each other and their parents?

To start with, both parents are long haired. Long hair is a recessive gene, so all the kittens have to be longhairs. Other than that, yes you can have vastly different kittens IF the parents are mixed breed, and it's far more likely if there is more than one father. For instance, if a pure Siamese mates with a non Siamese, the kittens will usually be solid black (that's a quirk of Siamese). They can be carrying some recessive Siamese traits, and as the mate with other cats, they can p these on as well as traits from the other mate. Down the line, if one of thes cats with recessive Siamese traits mates with another cat with recessive Siamese traits, an ordinary brown tabby can have another tabby, a kitten with tabby or solid color points on a short hair build (like Color point Short hair), a kitten with a Siamese build but solid or tabby coloring (looks like Oriental Short hair), a very Siamese looking cat, or an ordinary short hair. The right combination of genes could be mistaken for a purebred, but they are not really and their kittens could look like anything. Somali is a variant on tabby, and many Main Coon patterns are tabby. So both could be tabby mixes with many traits of these breeds. One kitten could also resemble a Somali if it got most of it's genes from the mother. A spotted tabby could resemble an Osicat. I'm hazy on what a Burmilla looks like. But they ALL have to be longhairs. Only if mom was an Abasinian-type with arecessivee longhair gene could you have a mixed long and short haired litter. Unless... she adopted some orphaned kittens.