The difference between VIP and MIP:
VIP is flexible port forwarding only sending the specified ports in the configuration and only in the direction configured.
MIP is for Mapped IP meaning a one-to-one bidirectional mapping of the outside ip address. These simplify configurations because you don't need to create both an inbound policy plus and outbound source nat policy.
What traffic is permitted is further controlled by the security policy on top of these nat objects.