Hi, welcome to silkysteps, not so different it's just that these theorists haven't been looked at on this thread xx
Both Robert Sternberg and Howard Gardener are psychologists and cognitive theorists. A few points to guide your research is that their cognitive theory examines the way in which children make associations and connections with things - eg. a tube becomes a rocket. It's thought that this understanding is a type of intelligence and suggests that children require many play opportunities so that they're able to make these connections through their first hand experiences, developing 'pockets of knowledge'
Graham Wallas is a psychologist who puts foward creativity as process - in that new ideas emerge as a process evolves. His
5 stage model explains the idea behind the theory - preparation, incubation, intimation, insight or illumination and verification. In addition to this he places importance on the unconcious mind and sleep as a componnet to solving problems.
Edward De Bono's theory places importance on creative thinking needing to be planned and organised, with problem solving needing to use a process or staged model - six thinking hats
There is also the nature nurtue debate and social, cultural & role model concepts that the
heinemann cypop 7 chapter will help explore.
I hope this helps a little, best wishes xx