Running a masternode is a form of staking, but more difficult to reach.
To stake coins you just need the wallet with some coins in it and depending on the coin the reward is calculated differently. Sometimes you get chosen by your coins age, so the longer you're holding the greater the chance that your coins will sign the transaction (the older your coins the greater the chance of getting a reward which is proportional to the amount of held coins) and sometimes you get chosen only by the amount of coins that you're holding (the more coins the greater the chance of getting a reward).
A masternode is combination of a staking wallet and a server. To run it you need a server, a stable connection, a minimum number of coins that will be used for staking (with Dash it's 1000) and time to main it. Instead of being chosen or not to sign a transaction a masternode is being constantly engaged and constantly paying out a certain amount of coins.
Thank you for your answers, I understand it now.
