If total light gathered is similar, stacking many shorter frames can approach the noise performance of one longer exposure, but the results are not always identical.

A single longer exposure usually helps with photon shot noise because you collect signal continuously. But very long exposures can become limited by dark-current/thermal noise as the sensor stays active and warms up. With many CMOS cameras, very long exposures can become less efficient, so stacking shorter frames may produce cleaner results.

Stacking is also preferable when reliability matters: if one frame is ruined by an airplane, person, vibration, or other transient event, you can discard that frame and keep the rest. That makes stacking especially useful in astrophotography and for scenes where moving objects need to be removed.

Multiple exposures are also commonly used for architectural work, HDR scenes, and removing tourists/people.

If your test showed little difference, that is plausible: for modest exposure times, the benefit of stacking over one clean long exposure may be small, and software processing can make the outputs look very similar.

In short: use one long exposure when it is practical and clean; use stacked shorter exposures when exposure times get very long, when you want to reject bad frames, or when you need flexibility in post-processing.