Why haven't you heard of YouTube stars Joe and Caspar?

YouTube stars Caspar Lee and Joe Sugg take on the use in their movie, Joe & Caspar Hit The Road USA.

Chances are you've never heard of Joe Sugg and Caspar Lee. The pair are YouTube stars, and we mean "stars" in every sense of the word.

Between them they boast over 14 million YouTube subscribers, 9.3 million Instagram followers and 8 million Twitter fans.

And now they're set to hit New Zealand.

British born Sugg, 25, and South African Lee, 22, have both been making vlogs, prank and challenge videos since 2011 on their individual channels ThatcherJoe and Caspar.

The pair first met through YouTube, before hitting it off after meeting in person in London and teaming up. Now they're touring the world together, meeting fans and making movies about their adventures.

Joe Sugg and Caspar Lee in the movie, Joe & Caspar Hit The Road USA.

Recently they unveiled their second feature-length film, Joe & Caspar Hit The Road USA, which was made with the help of BBC Worldwide.

The movie sees the duo going "head-to-head" in a series of contests and pranks as they tour America.

"It's more of a challenge-based thing, rather than just travelling around together; we're competing full-on this time," Lee says.

The film is a follow-up to their 2015 movie, Joe & Caspar Hit The Road, where they travelled around Europe.

"It was quite successful", Lee says, "which we're really thankful for. It's because of the viewers and the people who've supported us."

While they're in New Zealand Sugg and Lee will have the chance to meet some of their Kiwi fans at a live event at the ASB Theatre.

Though they love meeting the people who helped make their YouTube celebrity career possible, neither are comfortable with the term "celebrity".

"I think we're in a different league," Sugg says. "Personally, I never started YouTube with the intention of becoming a celebrity."

"It's kind of the best of both worlds. We're in such a great position because we get good views on videos and we do really well on YouTube, but when we're out and about we don't get that spotlight on us that most celebrities do.

"I just feel very lucky to be a part of the new platform that's starting to get bigger and bigger in the entertainment industry."

Caspar Lee and Joe Sugg in a scene from their movie the movie, Joe & Caspar Hit The Road USA.

"Some people on YouTube are recognised as [celebrities] and some people aren't." Lee adds. "I think we're lucky enough that we don't get bombarded with the whole thing. For us, it's just all about making the videos."

It really is all about the videos for these two. What gets them excited is vlogging, having camera crews follow them around and getting to share the exclusive content with the fans they're lucky enough to meet - while holding on to the creative control of being a YouTuber.

For Sugg and Lee, staying true to themselves and their viewers has landed them some "unbelievable" opportunities and taken them on some fun adventures.

Who: Joe & Caspar Hit the Road USA - Live
Where: ASB Theatre, Auckland
When: November 10
For more information visit ticketmaster.co.nz