I have a FortiSwitch 28C on my desk at this very moment :)
FortiSwitch 28C is a Layer 2 switch. You cannot route between VLAN' s. This is true of any Layer 2 switch. We do carry switch products that are Layer 3 and can indeed route between VLANs like you are asking. That is relevant to standalone mode. If you use FortiLink mode, it is indeed possible to route between the VLAN' s but at that point it' s the FortiGate doing it, not the switch.
In standalone mode there is a GUI and a CLI very much like FortiOS. It is a very reduced GUI and CLI as there are far fewer commands relevant to a switch vs a firewall. If you are curious I have attached a screenshot of the dashboard of my FortiSwitch 28C.
Even in FortiLink mode it is possible to access the switch via these same methods but obviously what you have the ability to change is different since you are managing VLANs and ports from the FortiGate now.
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Sean Toomey, CISSP FCNSP
Consulting Security Engineer (CSE)
FORTINET— High Performance Network Security