FortiGate VW Pair vs TP mode

AFAIK they are basically the same thing. VW Pair is useful if you have an existing FGT in NAT mode that you only need a single transparent connection amongts the routed connections. If you only have a need for transparent mode it can be easier to manage and less prone to errors/issues if you create a transparent VDOM on the FGT and manage it from an admin/management VDOM.

Tell us about your current environment and FortiGate config and the requirements for transparent mode/VW Pair and we can help steer you.