vmnic = A real phyiscal interface on an ESX host
vmknic = virtual network interface that is used by the VMKernel
veth = nothing, this isn't a real term, but it's probably the same thing as vswif
vswif = The virtual ethernet interface that is used by the service console
vmfs = VMware Filesystem, currently at version 3 is a journaled distributed filesystem used for storing VMs
I would also add that it is to the vmknic and vswif to which the VMkernel and Service Console IP addresses are assigned respectively.