Sorry about that. I tried posting a link to some different discussions about managed/unmanaged and I think it posted some erroneous content.
Anyway, an unmanged just does layer 2 switching. There's absolutely nothing to setup, not even an IP address. It's essentially "dumb"
If you need the switch to perform other services, like VLANS, QoS, STP, DHCP Server, Layer 3 routing, etc.. you'll need a managed switch. These aren't plug&play and require configuration before introducing them into your network.
the switch should come with a serial link cable. plug that into the back of the switch and the other end into a serial port on your computer. open hyperterminal, (this is if you are using windows), and create a connection to it. point the connection to the comm port that it is on. you will want to read the book for the switch to find the connection settings for the comm port. this will allow you to get into the config of the switch, set the IP address, password, etc. once the IP address and password are set you can install the switch. then from there you can open your browser on your computer and point it to the IP address and control it via web interface if the switch supports it. as far as the difference you can remote into the switch to check status of each port as far as excessive broadcasts, etc. also setting up VLANS to contain traffic, enable and disable single or multiple ports at a time, setup QoS, (quality of service), to give priority to specific protocols, (VoIP for example), setup logging of errors, check PoE status on ports, install SSL certificates on the switch for encrypted traffic, etc.