Apple Inc. (NASDAQ:AAPL) is expected to release a 128GB version of its upcoming iPhone, dubbed iPhone 6, but the company could restrict this option to the larger 5.5-inch model, according to a new report.

Apple’s decision to limit the 128GB option to the bigger version of the iPhone 6 is considered as the company’s move to differentiate the 5.5-inch model from the 4.7-inch variant, which is expected to feature a maximum storage capacity of 64GB,, a Chinese news website reported on Wednesday.

The report followed another rumor from earlier that day, which claimed that Apple could release 32GB and 64GB versions of the iPhone 6 on Sept. 19, a release date that is thought to be a calculated guess, because it suits Apple’s traditional iPhone-release cycle and supports similar claims made by Deutsche Telekom, a German wireless provider, in May.

According to the earlier rumor on Wednesday, the 32GB and 64GB versions of the 4.7-inch iPhone 6 could cost about $850 and $1,000, respectively. However, the report did not mention the possibility of a 16GB version of the device, which, if turns out to be true, could go against Apple’s practice of releasing an iOS device with three different storage options, MacRumors reported.

The diversity in storage capacity appears to be yet another attempt by Apple to differentiate the 5.5-inch iPhone 6 model from the 4.7-inch version of the phone.

According to other media reports Wednesday, many analysts believe that the bigger version of the iPhone 6 could feature optical image stabilization, or OIS, as a key improvement to the bigger handset’s camera while the 4.7-inch model might only sport an improved lens module, allowing it to focus on objects faster than the current iPhone 5s.

“In our analysis, we believe Apple chose to only include OIS camera technology in the larger iPhone 6 given that there is still a significant cost premium ($4 to $5) over standard auto focus solutions and that it provides a point of differentiation between the 4.7-inch iPhone 6 and the step-up model (5.5-inch),” analysts at Pacific Crest Securities wrote in a research note, obtained by MacRumors.