The Defer and Min Time statements are both outlet timers.

Defer - will delay or defer an outlet from changing its state for X amount of time.

Min Time - will insure an outlet stays in its current state for a Minimum Amount of Time.

The Defer and Min Time statements are the exception to the rule that program statements are processed in order - it doesn't matter where in your outlet program the Defer or Min Time are, they apply after all program statements are processed.

So when would you use one vs. the other?

Scenario: I've got a float that bounces up and down in my turbulent sump. I want to smooth that out so it's not turning my ATO on/off all the time.
Solution: Add a Defer to your ATO outlet program of a minute. That will eliminate the little bounces and only turn your outlet ON or OFF after it's been in that state for a full minute.

Scenario: I want to make sure my lights stay off for 5 minutes to cool-down in case of a power failure.
Solution: Add a Min Time of 5 minutes to your light outlet. Even if you try to turn them back ON in that time, they'll stay off.

So how are they used? Here's an example of each:

Defer 1:00 Then ON
Translated: Defer the ON state for 1 minute. (OFF would be immediate).

Min Time 5:00 Then OFF
Translated: Minimum Time of 5 minutes in the OFF state. (ON would be immediate)

There's more information on both of these statements in the Reference Manual.