Simple answer is managed switches allow you to interact with it using various tools. Connect via IP and a browser or telnet etc.., or you can use a serial or proprietary connection. SNMP traps, filtering, and so on. Unmanaged are dumb network devices. They have a job and they do it. Managed switches give you some flexibility and it really depends on the software as to what features your able to use. Need a processor and additional software so they will be more expensive. I imagine there will be others with more articulate responses but I wonder if there are any websites that disect this. It's just not that dificult a thing to figure out. Managed, Unmanaged. The name alone is implication enough to understand the difference.