Prince Charles and Queen Elizabeth II
Prince Charles and Princess Anne have a "combustible" relationship because the latter is stubborn and strong-willed. Pictured: Queen Elizabeth II, Prince Charles and Princess Anne watch the 2017 Braemar Gathering at The Princess Royal and Duke of Fife Memorial Park on Sept. 2, 2017 in Braemar, Scotland. Getty Images/Chris Jackson

Prince Charles and Princess Anne have a "combustible" relationship.

The Prince of Wales and Princess Royal do not agree all the time just like any other pair of siblings. According to Matthew Kirkham, a journalist for Express, Prince Charles and Princess Anne are very different in terms of personality. The former is "meek" and "defensive," while the latter is "stubborn" and "strong-willed." They also have different interests and friends, so it is no wonder that they have grown apart.

In Anthony Holden's book "Charles, Prince of Wales," the future king was disgruntled after learning about Princess Anne's confrontation with the members of the public. Holden noted that Prince Charles does not support Princess Anne's public outbursts and rage towards the press photographers. The Duke of Cornwall felt that what his sister was doing was "counter-productive."

Prince Charles "groaned" when he learned about Princess Anne in another confrontation with a group of anti-blood sports protestors when she was about to go fox hunting. One angry taxpayer reportedly confronted Princess Anne: "Who's paying you to do this?"

Prince Charles wasn't happy after learning about. According to the book, Prince Charles "knew what was coming next."

The exchange of abuse climaxed when the angry taxpayers replied to Princess Anne: "Well, we're paying you to do that."

Holden noted that it's a "royal sin" for the members of the Firm to fall into a confrontational situation with the members of the public. Prince Charles has been cautious with this and even perfected how to avoid such situations.

In addition, unlike Prince Charles, Prince William, Kate Middleton, Prince Harry and Meghan Markle, Princess Anne do not shake hands with the public. "We never shook hands. The theory was that you couldn’t shake hands with everybody, so don't start," Princess Anne explained.

"So I kind of stick with that, but I noticed others don't. It's not for me to say that it's wrong, but I think the initial concept was that it was patently absurd to start shaking hands. And it seems to me that it's become a shaking hands exercise rather than a walkabout if you see what I mean, so that it has changed," she added.

Although Prince Anne and Prince Charles don't agree on some matter, just like any brother and sister they have sweet and funny moments, too. Earlier this month, BBC's documentary showed how Prince Charles pranked Princess Anne.

The future king was seen sneaking up on his younger sister. He then tapped her back and surprised her. Princess Anne turned around and looked at her brother while laughing.