Is Dickon's upbringing different than that of Mary and Colin? If yes, how?

Certainly--Dickon is a boy from the working class. His sister, Martha, is a maid at the manor, and Dickon has been brought up in the dales among the animals. He lives in a small cottage with his family, and they have never had very much money. Additionally, he has never been properly educated. Dickon can expect to go into a far different life as an adult than Colin.
It is worth noting, however, that Mary's upbringing is also different to Colin's. While they are both of the middle class, Mary spent her early childhood in India with distant parents. She was mostly looked after by her Indian governess. This has led her to behave as if she is of a far more aristocratic class than she actually is, having been treated as such by her Indian servants. The family of a diplomat would not have been able to live so lavishly in England. Meanwhile, Colin has lived a strangely segregated existence in a house in which there is money, though little sign of it being spent recently. His father is often away, and Colin has always been taught that he is going to die. As such, he has had a rather sad life, despite the fact that he comes from a higher social class than Dickon and has spent little time with other children.