Optimum No Rinse is a rinseless car wash product.  It's perfect for those that live in apartments without access to a hose, wintertime washing, etc.  You typically mix 1 oz into 1-2 oz of water in a bucket when washing your vehicle.  It can also be used as a clay bar lubricant or as a quick detailer (1 oz ONR with 16 oz of water).  It's definitely one of my favourite detailing products!! 
  
Optimum Opti-Clean is a waterless wash product and is typically used to remove light dirt, dust, pollen, bird bombs, etc from your paint.  It's a great quick detailer and has the necessary lubricants in it so that it will not harm your paint surface.  My vehicles always have a waterless wash product and a couple of MF towels in the trunk.