Passive speakers require an external amplifier (such as a stereo receiver). Passive speakers are connected to the external amp via traditional speaker wire. Passive speakers do not require electricity, so they are not plugged into an electrical outlet. 

Powered or active speakers have a built-in power amplifier, so they do not require an external amp or receiver. You will normally connect to powered speakers using RCA or 3.5mm interconnects (NOT speaker wire). Powered speakers require electricity, so they need to be plugged into an electrical outlet. Sound bars, wi-fi speakers (e.g. Sonos) and desktop radios are powered.