FortiADC Full NAT vs Direct routing vs DNAT vs direct routing

[adam283849]

Hello i feel so confuse about 

FortiADC Full NAT vs Direct routing vs DNAT when i do Virtual server configurations

i worked alot  with F5 but i realy like FortiADC but i wish if i have simple explaination

could you please tell me

if i want to activate SNAT in F5 = Full NAT with source NAT pool right?

but my important question i want to disable SNAT in FortiADC = Do i need to use DNAT or direct routing 

Regards 

Adam