The filled spider chart below compares all primary iPhone models for talk time, screen size, and songs held. Each variable is mapped to an axis creating a 3 axis chart. Therefore, each iPhone is represented by a triangle and the triangle corners map to the phone’s capabilities for the selected variable.
As expected, newer models have greater capabilities and as a result the triangle that represents them is larger than the previous model. Over the years, iPhone screen size has not changed as much as battery life (talk time) and storage (songs held). For the selected variables, iPhones 7 and 8 have the same capabilities.

Spider chart comparing primary iPhone models for talk time, screen size, and songs held
This chart was built with the Aploris add-in for PowerPoint.