Piaget believed that children actively constructed their knowledge. For him a child`s thinking develops as gradual growth of knowldge and intellectual skills towards a final stage of formal, logical thinking. We can take from Piaget the idea of the child as a sense-marker (the child as an active learner and thinker)
However, Vigotsky focuses on how social interactions affected child`s language.
The difference between both is that for Piaget the child is an active learner alone in a world of objects, for Vigotsky the child is an active learner in a world full of other people.
The similarity between both is that neither of them neglect the individual cognitive development.
It is Bruner with other authors, like wood and Ross, who proposed Sacaffolding metaphorical concept.
Scaffolding refers to the particular kind of help, assistance and support that enables a child to do a task which they cannot quite manage on their own, but this help is temporary and can be put in place as the child develops knowledge and skills and is increasingly able to act independently.
It is important to remark that Scaffolding is based on the Vygotskyan promise of learning as a socially constructed process.
Scaffolding and ZPD are based on the need for interaction between the speakers, so improve their oral competence.
Both are based on the knowledge that has the child and what can achieve with the help of an adult or a knowledge person.