Here's a few things GNUnet replaces and why it's better:
Bittorrent is replaced by GNUnet "filesharing", it's trackerless, it provides a search function, users can adjust their level of anonymity for publishing, downloading, and searching.
DNS is replaced by "GNS", it covers the "decentralized" and "secure" points in Zooko's triangle, it a pet name system.
VPN is replaced by GNUnet VPN, which is just VPN over GNUnet so it can take advantage of the p2p network.
TCP/UDP/SPDY/QUIC is replaced by "cadet", takes advantage of the p2p network.
There's also a DHT.
And there's lots of other stuff that's in-progress.
We should maybe include a "GNUnet in 5 minutes or less" on the website. The old LEGO analogy is nice, and lynX did a great comparison here: https://secushare.org/img/stack-comparison.png
We don't really need the ISO OSI model here, but even this can be added, as we've already used it throughout the years to compare to the GNUnet stack.
Bittorrent is replaced by GNUnet "filesharing", it's trackerless, it provides a search function, users can adjust their level of anonymity for publishing, downloading, and searching.
DNS is replaced by "GNS", it covers the "decentralized" and "secure" points in Zooko's triangle, it a pet name system.
VPN is replaced by GNUnet VPN, which is just VPN over GNUnet so it can take advantage of the p2p network.
TCP/UDP/SPDY/QUIC is replaced by "cadet", takes advantage of the p2p network.
There's also a DHT.
And there's lots of other stuff that's in-progress.