Slowly but surely, Apple 's (NASDAQ:AAPL) plans with its iPhone 6 lineup seem to becoming clearer. While rumors have been making rounds for a while that this year's launch will include both a 4.7-inch and 5.5-inch version of the iPhone 6, it wasn't clear how -- beyond screen size -- Apple would differentiate the two phones from previous models. But new rumors and reports are helping us piece together how Apple may plan to clearly set the models apart as a higher-end experience.

iPhone 6 4.7-inch and 5.5-inch mockups pictured with the 4-inch iPhone 5s. Image source: 9to5Mac, used with permission.

Clear positioning
Currently, Apple's flagship iPhone 5s lineup offers a minimum storage capacity of 16GB and maximum capacity of 64GB. But Apple may be taking a different approach to storage for the iPhone 6 lineup, according to Wei Feng.

The 4.7-inch iPhone 6, in line with another new report from Chinese web portal Tencent, will come in only 32GB and 64GB storage capacities. The move to drop a 16GB version of the phone will reinforce Apple's positioning at the high-end of the market. Such a move is especially important after the recent the Amazon Fire Phone was launched with a minimum capacity of 32GB, doubling entry-iPhone 5s storage capacity, despite the fact that the pricing for its entry-level version of the phone was the same as Apple's iPhone 5s. Not matching or exceeding Amazon's storage offerings would give the e-retailer a definite marketing advantage.

But Apple also plans to change up the typical storage options with the larger 5.5-inch iPhone 6, too. With the larger phablet-sized smartphone, Wei Feng asserts that the phablet-sized phone be available in a 128 GB variant -- larger storage capacity than in any other iPhone. Even more noteworthy, the capacity matches the highest-end iPad Air. 

MacRumors renderings, by Ferry Passchier, of the alleged 4.7-inch and 5.5-inch sixth generation iPhone lineup. Photo used with permission.

Another way the larger iPhone 6 will see differentiation, according to the reliable and well-connected KGI Securities analyst Ming-Chi Kuo, is with the camera. The 5.5-inch iPhone 6, Kuo predicts, will be the only model to offer optical image stabilization.

Finally, the A8 processor will obviously be a differentiating factor in terms of performance and efficiency. If Apple keeps up its recent pace with system on a chip evolution, the A8 should be the best processor at the time of launch. Both phones are rumored to sport Apple's next-generation processor.

A reason to upgrade
With these larger iPhones, Apple will undoubtedly aim to do more than simply offer phones with larger displays. Instead, Apple will likely strive to have a well-defined new high-end experience for customers who desire to take their smartphone use to new levels.

This had better be the case, at least for the larger of the two alleged iPhone 6 offerings; the rumor mill believes that the entry level phablet-sized iPhone 6 may even receive a price boost of $100 over the iPhone 5s, costing $299 with a contract instead of the typical $199.

But will Apple be able to summon enough new features in these larger phones to get users to upgrade in droves? Even a better question: Will Apple attract many new buyers by finally entering the phablet space?

When Apple launches the iPhone 6 lineup later this year I'll be watching to see how Apple will attempt to redefine its smartphone lineup. Can it do so significantly enough to clearly position itself as one of the best premium offerings in the smartphone market?