As far as i know, there are 4 main types of network interfaces in linux: tun, tap, bridge and physical.
When i'm doing sys admin on machines running KVM, i usually come accross tap, bridge and physical interfaces on the same machine, without being able to tell them apart. I can't see any significant differences in
ifconfig results, as in
How can i know if an interface is tun/tap/bridge/physical ?
note: I don't claim there is no other types of network interfaces in linux, but i know only this 4 ones