Is a UPS or a power station better for protecting a computer?

A UPS, because the transfer time is what matters: it takes over within milliseconds when the mains fails, which is what stops a machine rebooting. A power station holds far more energy but most models are not designed to switch over that fast.

Both devices contain a battery and an inverter, and they are engineered around opposite priorities.

What a UPS is built to do

Cover the gap. The mains is present almost all the time, so the battery is small and the switchover is fast. The specification that defines the product is the transfer time, followed by whether the unit corrects voltage as well as replacing it.

What a power station is built to do

Hold energy. The battery is large, the inverter is substantial, and the unit is designed to be carried and to run appliances for hours. Some models offer a pass-through or an uninterruptible mode; whether a particular one does, and how fast it switches, is stated by the maker or not at all.

Sizing them differently

A UPS is sized in the minutes needed to save work and shut down cleanly. A power station is sized in the hours a load has to survive. Trying to make one do the other job produces either a very expensive UPS or a computer that reboots anyway.

The specification most often skipped

Battery replaceability. A UPS battery is a consumable with a service life, and whether it can be changed — and whether replacements are sold — decides what happens to the unit in a few years.