The main difference between inline traffic interrogation (TAPS) and traffic mirroring (SPAN) lies in how they handle network traffic for analysis purposes. TAPS, or Test Access Points, are hardware devices that create a copy of the traffic between two network points without altering the data. This means TAPS can transmit both send and receive data streams simultaneously on separate dedicated channels, ensuring all data, including physical layer errors, is received by the monitoring or security device in real-time. On the other hand, SPAN, or Switch Port Analyzer, is a feature that duplicates network packets seen on one port to another port for analysis. However, SPAN ports can filter out physical layer errors, which may limit the types of analyses that can be performed as some errors will not be represented in the mirrored traffic.