Since the first iPhone was launched in 2007, Apple (NASDAQ:AAPL) has updated its flagship smartphone about every year. But it's only about every other year that the company gives the phone an entirely new form factor. This year is suspected to be one of those years. Among other key changes in form-factor, the ever-active Apple rumor mill believes the tech giant is planning a big boost to the iPhone's display size.

The key differences?
The consensus is that the new iPhone models will sport both a 4.7-inch and 5.7-inch display, putting them near the Samsung Galaxy S5's 5.1-inch screen size. While a number of mockups and part leaks have surfaced, there have been only a few potential full-fledged photos of the entire form factor in all its glory. That said, here are two of the few photos to surface. These are floating around Twitter, posted by Sonny Dickson.

At first glance, these iPhones might not look all that different from the ones we, or our friends, may own. But there are several key differentiating factors to the form factor.

First and foremost, the displays are considerably larger. To illustrate how the models compare with Apple's current product lineup, MacRumors commissioned these renderings.


MacRumors renderings, by Ferry Passchier, of alleged 4.7-inch and 5.7-inch sixth-generation iPhone lineup (middle) next to iPhone 5s (left) and iPad Mini (right). Photo used with permission.

The other most notable change to the physical feel of the iPhone will probably be its thickness (or lack thereof, more specifically). Alleged iPhone 6 schematics suggest that the models could be closer to the 6.1mm thickness of the iPod Touch, down from the iPhone 5s' thickness of 7.6mm. 

Then there're the more subtle changes. Consider the rounded case edges that resemble the latest-generation iPad Mini model and the iPad Air. Then there's the alleged improved pixel density: 416 and 365 for the 4.7-inch and 5.5-inch models, respectively, which compares with a pixel density of 326 for the iPhone 5s. It's also rumored the phone could adopt thinner bezels -- especially in the larger model, thanks to the possible adoption of a sapphire crystal display.

Simply put, the latest-generation iPhone models will probably have more room on the display while also making the design sleeker and slimmer.

Big enough changes?
Of course, there will be internal changes, too -- like the rumored faster and more efficient A8 system on a chip, but it's always worth wondering: Will these changes be enough to continue to attract droves of new iPhone buyers?

Apple Store

Fortunately, the market for larger smartphones has already proved to be hot. Even Apple acknowledged that it may be considerably missing out. An internal Apple document that surfaced in a Samsung-Apple trial earlier this year, first posted by Re/code, acknowledged that 91 million of the 228 million in incremental growth of smartphone sales in 2012 came from smartphones with screens larger than 4 inches. The rest of the growth? Mostly from the segment of smartphones priced less than $300 -- a market Apple probably won't be willing to enter.

Apple investors should hope the company really is prepping new iPhone models with larger displays. Selling larger smartphones sounds like a smart strategic move for the company at this point.

Rumors point to the usual September launch for the latest iPhone models.

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Daniel Sparks owns shares of Apple. The Motley Fool recommends, Apple, and Twitter and owns shares of and Apple. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.