VPNs do not allow you to connect two devices directly, they have to go through the VPN. They also do not allow you to connect devices that are not on the VPN. Iroh does P2P connections and punches holes through NATs when needed, so you can connect directly to devices on different networks that are behind firewalls.

From my VERY brief understanding: this is like if you want the hole-punching of a VPN, but your stuff is public, so not only do you not want all the security of a VPN, but it works against you. But I'm happy to be corrected!

vpns typically add at least one hop. this has the possibility of connecting directly via hole punching