Amid the inevitable comparisons between the two women, William has insisted that "no one is trying to fill my mother's shoes".
Yet his actions have ensured Diana is remembered everywhere Kate turns.
He proposed with his mother's diamond and sapphire ring, explaining afterwards that "this was my way of keeping her close to it all". Kate said it was "very, very special" and promised to treasure it.
Although the couple decided not to follow his parents and marry in St Paul's Cathedral, their choice of Westminster Abbey is heavy with symbolism.
It was at the abbey that the 15-year-old William and his younger brother Harry walked up the aisle behind their mother's coffin following her death in a Paris car crash in 1997, their heads bowed in silent misery.
Diana's brother, Earl Charles Spencer, made headlines that day with a speech seen as critical of the royal family's treatment of his sister.
On Friday, he will sit near the front of the Abbey, although behind Kate's family, not William's.
Last week, William reportedly took Kate to lay flowers at Diana's grave at her family's Althorp estate in Northamptonshire, central England.
Harry, the best man, said recently that their mother will be in their thoughts on the big day.
"Myself, my brother and my father, there will be all sorts of people and the rest of the family that will no doubt be thinking about it. And I hope she would be very, very proud that the big day has come upon him," he said.
Diana's constant presence has sparked inevitable comparisons with Kate, but commentators say the women have different characters, different backgrounds and crucially, their relationships with their princes are worlds apart.
Kate will be 29 when she marries 28-year-old William and she has a university degree and several years of work behind her. They have also been in a relationship for almost eight years, and appear very much in love.
By contrast, Diana was a shy, naive 20-year-old when she married Charles. As the 32-year-old heir to the throne, he was under pressure to find a wife and produce an heir. They dated only for a few months before tying the knot.
As the world now knows, Charles was also in love with someone else, Camilla Parker-Bowles, with whom he would later have an affair and finally marry in 2005.
Diana also married her prince in a different era, when much was made of her virginity -- a pre-requisite for the woman marrying the royal heir, even in 1981 -- and when she called her fiancee 'Sir' right up until the wedding day.
Andrew Morton, the author who laid bare Diana's unhappiness in his 1992 book "Diana: Her True Story", said there was a wide chasm between her and Kate.
"The difference is that Charles and Diana had a very short courtship, they didn't meet that often, they didn't know each other that well," he told AFP.
"This time around they have been courting for eight years, they have lived together, they know what side of the bed each other sleeps on. They are very much like an old married couple, quite frankly."
Kate is also more sure of herself than Diana was, helped by the support of her family -- she is close to her mother, Carole, and her sister Pippa is her maid of honour. Diana's parents divorced acrimoniously when she was young.
There are similarities, however, not least in the way they appeal to the media. Diana was pursued by photographers right from the announcement of her engagement, while Kate has also had to call in the lawyers to protect herself.
Yet although Kate has star quality, she has a long way to go to match the adoration directed even now at the "People's Princess".
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