1) VPN in new switch
Unless you have a 6500 switch you can not do VPN in a switch.
VPN is normally L3.
2) Difference between VLAN and VPN
they are not the same. It is like comparing a boat with an airplane two totally different things for totaly different purposes but both can carry packets to and from destinations.
a vpn is generally used when you connect a faraway LAN o'r computer to the local LAN to allow for a "secure" encrypted connection
a VLAN is in general a separator of broadcast zones. no encryption.
two totally different things but both send packets.
Good luck