Self-discipline is mostly about behaving yourself in a military department and everything connected with giving orders as well as following to the orders with no discussions and comments. Self-development is like motivating yourself for achieving certain types of goals, also, one should has clear and detailed plan about his personal growth at least for a year forward. As you can see, both of terms begins with "self", that is clearly means that one should better be concerned about himself with no judging statements towards others' side. My humble suggestion to everyone, always keep in my mind that " An expert in anything was once a beginner". It clearly says that whenever you see an expert in any sector do not be so admired about his elusive achievements because anyone can do that, certainly, it takes huge amount of time and effort, just do not panic at the beginning.