According to the rumor, Nokia Lumia 720’s code name is Zeal while Nokia Lumia 520 is Fame. They are running on Windows Phone 8 operating system.
Lumia 720 is reported to have a 4.3-inc display with CBD, dual-core processor clocked at 1 GHz supported by 512 MB of RAM and 8 GB of internal storage, microSD slot, HSPA+ connection, and two cameras (6 megapixels on the back and 2 megapixels on the front).
Lumia 520 will have a 4.0-inch display with Super Sensitive Screen technology, dual-core 1 GHz processor with 512 MB of RAM (like Lumia 720), 8 GB storage with microSD slot for expansion, as well as 5 megapixels camera without front-facing camera.
The two Lumias are rumored to be sold in the market at affordable price. Consequently, the display resolution is only WVGA in order to reduce the price.