It is just a MEDIA Center Device which can play your all Audio/Video formats & you can also enjoy home video's etc, So its cloud based device. But you can't work like a Pc.
NUC = Next Unit of Computing... its nothing but a mini PC. however it usually doesnt have the RAM and HDD in-built. it has the board, processor, fan and power supply. it has internal slots for RAM and HDD and external ports to connect other devices... :k
have you known about Raspberry Pi. its similar to that.