As a system designer, you may choose to apply either time-based or signal-based synchronization. The decision is typically tied to the devices involved, the required synchronization accuracy, and the distance between nodes. Hybrid topologies are also common, especially for complex multi-node systems.
In time-based synchronization, the internal clock of each node is synchronized to a reference clock. This allows executing and correlating synchronized measurements with an absolute sense of time (date and time). Synchronization over long distances is possible by using globally available master clocks like the time signal provided by Global Navigation Satellite Systems (GNSS).
However, absolute time is not always required. For some applications, such as high-speed sampling, one of the goals is highly accurate synchronized execution. This is achieved by sharing exact trigger and clock signal pulses across nodes. This method is referred to as signal-based synchronization.