A better source of info than the manual is the Unofficial Users Guide stickied at the top of the forum. Give that a read, it is organized by topic, so you don't have to read it all at once. In the mean time, Defer is a particular type of delay. It delays an Outlet from changing states for a set time. It is typically used with probe measurements to buffer out minor fluctuations. For example:
If Temp < 76.0 Then ON
Defer 5:00 Then ON
This might be used to control a heater. The Defer requires that the temp be less than 76 for an uninterrupted five minutes, before changing the Outlet to ON. The defer applies to the Outlet, not the condition. So you only need one for ON and another for OFF as necessary.
Todd