The term "Snowballs" refers to flowers that has been coated with THCA isolate crystals or in most cases both THCA and CBD. This makes it extra rich and create a very strong relaxing psychoactive effect due to high concentration of CBD presence. Much like Moon rocks except it does not contain any concentrated oil.
Purple Dream, a potent even blend of sativa and indica, is one of the most popular marijuana strains of all time. So is Purple Kush, a mightily powerful pure indica (the ratio of sativa to indica is unknown). Together they were used to breed Purple Dream, a mild but effective indica-dominant hybrid. Some sources use this name to describe a different strain, a cross of Blue Dream and Granddaddy Purps, but the Purple Kush cross seems to be more popular.