Difference between charging icons - does it mean anything?

Question

Sometimes I see this:

instead of this:

is there a difference? do they mean different things? One is filled in dark, the other is more transparent - the battery/charge icon..

Answer 1

Empty battery icon with lightning bolt means the device is plugged-in and using power but the battery is not charging. Your Mac is using power directly from the cord.

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Full battery icon with lightning bolt means the device is plugged-in and the battery is charging. Your Mac can use power from both the cord and battery.