What is the between a learning disability and mental retardation?

A learning disability involves normal to above average or superior aptitude, but an inability or impaired ability to process information given in a particular form. For example, a person with dyslexia may have trouble processing written information, but can understand and retain the same information if it is presented in auditory form (ie. can't remember what they read in a book, but remembers the audiobook of the same book perfectly).

Mental retardation involves limited aptitude due to abnormal or incomplete brain development.