TAP vs SPAN

• To TAP or SPAN?

(Test Access Point)
A simple hardware device that copies all network  traffic for monitoring, analysis, and security

(Switch Port Analyzer / Mirror)
Software built into switches and routers that copies
selected packets passing through the device

To summarize, here are the top 10 reasons why network TAPs are preferred over SPAN ports:
TAPs create an exact copy of the bi-directional network  traffic at full line rate, providing full fidelity for network monitoring, analytics and security.
https://www.gigamon.com/content/dam/resource-library/english/white-paper/wp-tap-vs-span.pdf