Skycoin (SKY) is the native coin of the Skycoin Internet platform. You’ll be able to buy the coin on the project’s website, as well as to trade it against other cryptos on a number of exchanges.
Decentraland (MANA) is currently based on cryptocurrency Ethereum protocol. You can trade this digital asset on the fair number of exchanges. For example, Binance features MANA/BTC currency pair.