You may think that a Slurpee and a Slushie are two words to describe the same thing. If so, you would be wrong. A Slurpee and a Slushie are actually quite different.
Slurpee
A Slurpee is a frozen beverage exclusively sold at 7-11. It has a smooth texture of tiny crystals, appears to be almost foam like, comes out of a machine similar to how soft serve ice cream is dispensed, and comes in some amazing different flavors licensed through other companies (Mountain Dew, Coke, Fanta, etc). A Slurpee is a sophisticated product that you would be hard pressed to replicate without the special equipment needed to make it. The soft smooth texture is what really makes makes a Slurpee a Slurpee.
Slushie
A Slushie (sometimes known as a ‘Slush Puppie’ however is essentially a cup of crushed ice with some some colored flavoring liquid poured over the top. It is a combination of two separate individual components: the ice (coarse larger ice shavings) and the liquid flavoring (the syrup). The flavor is a direct result of the flavoring liquid that you choose. This is a very simple product, comes in very limited generic flavors (think grape, cherry, etc), and can be replicated fairly easy without fancy equipment. Imagine a snow cone that you smashed up; a Slushie.
Bottom line:
You want a Slurpee.
