Dear Etta,

You ask if there is a difference between executive functions and cognitive development. Your question could be answered through a short answer or a long answer. What follows is a short answer to your question.

Of course, there is a difference between executive functions and cognitive development. As you certainly know, executive functions, generally referred to as executive function and cognitive control, are a set of cognitive processes that are necessary for the cognitive control of behavior, such as selecting and successfully monitoring behaviors that facilitate the attainment of chosen goals, such as solving, for example, a cognitive problem. Executive functions include basic cognitive processes such as attentional control, cognitive inhibition, inhibitory control, working memory, and cognitive flexibility and the like  Higher order executive functions require the simultaneous use of multiple basic executive functions and include planning and fluid intelligence such as reasoning of several types (e.g., induction, deduction, abduction) and problem solving. A working definition of cognitive development is to say that cognitive development is a process of successive differentiation and integration of  different dimensions, variables, perspectives, and so forth. Accordingly, we may say that executive functions, such as inhibitory control and cognitive flexibility, lie at the heart of cognitive development. To a great extent, the more we are cognitively flexible and capable of inhibiting irrelevant cues, the more cognitively developed we are.

For the sake of clarity and substantiation, let me appeal to a Piagetian liquids conservation task. Globally speaking, on this task, children view that a certain amount of water passes from a low and wide container, A, to a higher and narrower one than A, say, B. Children are then asked to say if there was more water in A than there is now in B; if there is now more water in B than there was in A; or if the water contained now in B is the "same thing" of water than that it was contained in A. Children are also asked to justify their answer to the previous question. As you certainly, pre-operational, non-conserver children tend to say that there is more water in B than there was in A. Usually, these children say that this is the case because the water in B gets higher than in A. We can say that non-conserver children’s wrong answers are due to their inability to inhibit an irrelevant perceptual cue as far as liquids conservation is concerned, that is, the highness of container B. Thus, their cognitive functions are still, say, poorly developed, and they are little flexible and decentered in cognitive terms. This is so, because non-conserver children are not yet capable of thinking that the water in B gets higher than in A, but B is also narrower than A. In contradistinction, conserver and operational children say that the amount of water contained in B is the same amount as that that was contained in A. Conservers tend to justify their correct answers by invoking one of the three Piagetian operational arguments: identity, that is, the water -- children say – only passed from A to B, and no water was added or subtracted when this passage occurred; reversibility, that is, if one passes – children say – the water from B to A, it would remain in A as when it was there before being passed to B; compensation, that is, the water gets higher in B than in A, but B is narrower than A. When invoking one of these arguments, not only do children show that they are able to inhibit irrelevant perceptual cues and, hence, that they are relatively advanced if their executive functions, but also that they are relatively flexible in cognitive terms because they are capable of decentration and able to integrate into a coherent whole the highness and width of both container A and B.    

Much more might be said of cognitive functions and cognitive flexibility. I hope that this Piagetian example show you what is mainly at stake when of speak of executive functions. The example also shows that the relatively fancy concept of executive functions is not as different from Piaget’s ideas on centration and decentration, differentiation and integration of dimensions or perspectives, cognitive flexibility, and the like, as is generally claimed. This is, however, an example of psychologists’ inclination to appeal to apparently new concepts when older ones had already been coined. As I see it, this procedure partly explains what the neo-Popperian Paul Meehl (1978) once called the slow progress of soft psychology (see, for this respect, his article published in the Journal of Consulting and Clinical Psychology).

I Hope that this show you that there are differences between executive functions and cognitive development, but that these concepts are intertwined.

 Best regards, Orlando

am very much gratful prof

I Was about to answer but I cannot do it better than Orlando Lourenço. I also say "thank you"

You may still have something new to add, i will appreciate 

I think you see the difference when you work with individuals with Traumatic Brain Injuries who sustained frontal and temporal lobe damage: loss of impulse control, rigidity of thought, inability to organize thoughts, problem solving skills based on what Piaget would refer to as decentering and loss of higher level memory and language processing. They had at one time gone through the levels of cognitive development and  I think because of this and because of the brain's ability to reorganize and neuroplaticity, many of them regain these ailities, depending on their age and of course the extent of the damage.

Thanks