So what are the differences between the two iOS handsets?

iPhone 6 and iPhone 6 Plus
Size and Display
The main difference is that the iPhone 6 features a 4.7-inch diagonal display, and the iPhone 6 Plus has a whopping 5.5-inch diagonal display.

This also means the iPhone 6 Plus has a larger overall size, entering "phablet" territory.

Battery Life
The iPhone 6 Plus is larger, so it contains a larger capacity battery. This means the iPhone 6 Plus gets significantly longer battery life than the iPhone 6. Check here for a rundown of expected battery life on the iPhone 6 and iPhone 6 Plus.

Camera
The iPhone 6 Plus has the same camera specs as the iPhone 6, with one difference. Only the iPhone 6 Plus will include optical image stabilization (OIS), which can improve clarity in low-light situations by reducing camera shake.

Price
Across the board, the iPhone 6 Plus costs $100 more than an iPhone 6 equipped with the same amount of storage space. Check here for pricing tiers on the iPhone 6 and iPhone 6 Plus.