Okay so there a lot of understandable confusion about creams that are vitamin A cousins (also called retinoids) because the names are all similiar. When you say retinal micro gel 0.4%, I'm thinking you meant Retin A micro gel 0.4%.  Renova and Retin A are basically the same thing in that they are both tretinoin (the generic name).  Renova is formulated in a more moisturizing base for dryer skin types specifically for older patients using it to repair sun damage.  The gel works also for those issues even though it's formulated for younger, oilier skin with acne.  Retinoids work for both acne and to repair sun damage and the aging associated with it.  The difference in the percentages is usually not important except for more severe acne when the higher %s may be helpful.