What is the difference between a Tap and a SPAN port?

What is a SPAN port? 

SPAN (Switched Port Analyzer) is a dedicated port on a switch that takes a mirrored copy of network traffic from within the switch to be sent to a destination. The destination is typically a monitoring device, or other tools used for troubleshooting or traffic analysis.

SPAN ports present a readily available mechanism through which to access detailed packet information.

What is a SPAN port?