What does just the jackpot mean on Mega Millions?

Second-tier prize amount is $1 Million ! Just the Jackpot Play offers 2 chances to win the Mega Millions Grand Prize for $3. Just the Jackpot wagers are eligible for the Mega Millions Grand Prize ONLY ! Just the Jackpot wagers are not eligible to win any other prize (non-Grand Prize) in the Mega Millions game.
how powerball lottery works