They're completely different tools with different purposes. Ntop is a tool you run on your network to introspect network flows between various hosts. The iftop

They're completely different tools with different purposes. Ntop is a tool you run on your network to introspect network flows between various hosts. The iftop utility provides a look in to what is flowing on an interface on your local machine. With ntop, you can aggregate collectors from many locations in order to develop a detailed understanding of how data flows in and out of your network.