What's the difference between 250W and 400W photography lamps for indoor still life photography?

Generally speaking, it is the difference in brightness.

If the light is on all the time, the power and brightness of the light are different, and the power consumption is also different.

If it is a movie lamp, it is mainly because the flash index is different, in fact, the brightness is different.

There is no difference in other aspects. Generally speaking, it is better to choose a movie lamp with higher power, because there will be an adjustable brightness knob on it, and the flash index can be selected as needed; But if the battery is low, when you need a large index flash, you will be overwhelmed.