It's all virtual, even the interfaces. You get one virtualized interface, and you can see that in lspci. VMware/VirtualBox choose the best interface for internet and does NAT by default.
If you want to attach more interfaces, you'll have to go to the network editor and create more 'vmnet' interface that you bridge to real interfaces. I don't know the equivalent with VirtualBox, it hasn't worked well for my usage and always let me down when I gave it a chance.
Bridge gets you direct access to the network. NAT is kinda like behind a firewall. Unless you want access directly to specific network interfaces, NAT is just fine.
