The topic is huge and is not conveniently summarized in few words. Most answers can also depend on your understanding of the terms, what does "D/R" mean to you? Recovering from a disaster only? What about data availability? Recovery time? Amount of acceptable data loss? Search online for these topics and do some reading.
Here is one link to get you started.
http://www.brentozar.com/archive/2011/12/sql-server-high-availability-disaster-recovery-basics-webcast/[/url]
There are no special teachers of virtue, because virtue is taught by the whole community.
--Plato