The active rapid growth of certain Acropora specimens can mimic bleaching  and appear very similar, and it takes experience and a trained eye to determine the difference in many instances.  This macro image shows a coral that is growing rapidly and a close inspection will show healthy tissue in the absence of color.  The polyps are large and visible as well as the sight of several new growth tips forming.  A bleaching coral will not show any new growth and polyps will be non existent or barely visible as health declines..  Careful inspection and daily observation will help to sharpen your ability to determine this factor.  This coral is called the Red Planet and was acquired from ORA coral farms.