Differences between Bitcoin-Qt and Bitcoind ???

[chegmarco]

Hello.
   I would like to know what exactly are the Differences between Bitcoin-Qt and Bitcoind ?
And can install and use both (Bitcoin-Qt and Bitcoind) at once?

Thank you.

[achow101]

bitcoin-qt is bitcoind but with a GUI. bitcoind does not have a gui and can only be interacted with through the JSON-RPC interface. You can run bitcoin-qt and bitcoind simultaneously but you will need to point each one to a different data directory (and thus it will download the blockchain for each datadir and have different wallets). They cannot share the same datadir.