"Snarky" is used to describe speech with a specific emotional tone, typically a form of sarcasm informed by cheekiness and a mild, playful irreverence or impudence. When the dominant intent of the communication is to express or convey direct or judgmental rudeness, the sense of mild cheekiness is lost and the overall communication crosses the line to become "snide."
The young music reviewer's snarky comments about the aging rock star's choice in clothing ultimately cost her an interview with the star months later.
sarcasm with an extra dose of snark: a biting remark that goes beyond mere snark or sarcasm, the preferred method of communication for professional smartasses
Sarcasm: "I only come to Jiffy Lube for the free coffee."
Snark: "Well, at least the price is right."
Snarkasm: Asking the Jiffy Lube cashier if she ground the beans herself.
Sarcasm: "Gee, thanks. I've always wanted a Chia Pet."
Snark: "I hope you kept the receipt."
Snarkasm: "Were they out of fruitcakes?"
Sarcasm: "So where's the rest of it?"
Snark: "Five inches is huge if you're 11."
Snarkasm: "Jesus! My mother has a bigger penis."