Soho routers offer basic capabilities - they can route and do NAT/firewall functionality between two interfaces...an inside and outside one. They can even run a routing protocol like RIP to communicate and exchange route information with other routers - so sure they can route between multiple nets.
"real" routers on the other hand can do just about anything you want them to do.
1) performance - ability to route millions of packets per second, able to handle tens of thousands of routes
2) modular - interfaces can be anything from a T1 to a T3, from 10 Base-T to FDDI, from SONET to ATM to gigabit ethernet...anything. Some routers have 100s of interfaces.
3) Features - full support for Quality of Service voice/video/data, indepth management, debugging and logging options
4) troubleshooting - tons of information on exactly what is happening to a packet as it moves thru the router
that's what I can think of off the top of my head.