The main difference between DC power supply and AC switching power supply lies in the current form and working principle of their output. Here are some key differences between them:

1. Output current form: The current output by DC power supply is a DC current with a constant direction, while the current output by AC switching power supply is an AC current with a periodic change in direction.
2. Working principle: DC power supply provides a stable output current by directly converting DC voltage. The AC switching power supply obtains the required output current by converting the input AC voltage into a high-frequency pulse signal, and then undergoes rectification, filtering and other links.
3. Efficiency: Generally speaking, AC switching power supply is more efficient than DC power supply because it can adjust and control the output current by adjusting the switching device to reduce energy loss.
4. In most cases, the output current of AC switching power supply is more stable because it needs to go through multiple links of circuit adjustment and filtering to make the output smoother.

In general, DC power supply and AC switching power supply have their own applicable application scenarios, and choosing the appropriate power supply type depends on the specific needs and application requirements.