All four ports provide the same amount of power and can charge phones, iPads or tablets. However, for best results it’s important to keep in mind:
The two ports labeled with the phone icon are wired with the standard Universal Serial Bus (USB) specifications.
The two ports labeled with the phone and tablet icons are equipped with resistor values that will communicate with the connected device to inform it that up to 2.1 amps of power can be drawn from this port. Note: Using this port to charge iPads and tablets will help charge these devices faster than using the ports with only the phone icon printed above it.
Certain tablets and/or versions of operating systems may charge faster on the tablet specific ports. Feel free to alternate from one port to the other if you feel your devices charge faster on either of the ports.