A screen replaces the four LED dots with an exact percentage, which turns a guess into a number. The difference matters most at the bottom of the range, where a single blinking LED could mean anything from a useful top up to nothing at all.

Better displays add live charging information: the wattage currently flowing out, sometimes the voltage and current, and an estimate of time remaining. That tells you at a glance whether a device is actually fast charging or has quietly negotiated a slow rate.

On a bank you rely on during a power interruption, knowing the real state of charge before you leave the house is the whole point. A percentage is actionable in a way that a row of dots is not.