Whilst Elizabeth was more serious and mature beyond her years, Margaret was the vivacious life of the party.
In fact, their father King George VI famously said that whilst his eldest daughter Elizabeth was his pride, Margaret was his joy.
Royal historian Dr Kate Williams also remarked on the sisters' distinctly different personalities in the documentary The Royal Family at War.
"Elizabeth was conscientious, dutiful, organised, methodical, always doing exactly what was expected of her," she explained.
"Margaret was impulsive and fun. She was often naughty, she had an imaginary friend called Cousin Halifax that she’d blame for everything that went wrong."
Despite their sisterly tiffs, royal experts say that the Queen and her younger sister shared a close bond.
"There’s some lovely archive footage of Elizabeth and Margaret when they were growing up," says royal expert Victoria Arbiter.
"It really speaks to the close relationship they shared and you can understand why. They didn’t go to regular schools, they were each other’s best friend."
As the sisters grew up, they remained close. According to Vanity Fair, Margaret installed a direct line to Buckingham Palace from her desk at Kensington Palace, allowing the two sisters to speak on the phone whenever they pleased.
Princess Margaret died in 2002 at the age of 71 after suffering from a stroke.
According to The New York Times, the usually reserved Queen Elizabeth II "was seen dabbing her eyes with a handkerchief" at the funeral service at Westminster Abbey.