The most obvious change is size. The original iPhone was 2.4" x 4.5'', while the iPhone X: 2.79" x 5.65". The screen has also come a long way in 10 years. The original iPhone has a 3.5" LCD screen ...
If you're looking to buy an iPhone, you may be asking yourself a combination (or all) of the following questions: How much storage should I buy? Should I buy an older model for less money?