Outdoor and pool use
A digital outdoor timer is built for weather: rain, dust and temperature swings. A digital pool timer is the same idea applied to pool pumps and pool equipment, where the schedule controls filtration and cleaning cycles. A pool pump timer is the pump-specific form of the same family.
What makes an outdoor timer different
The difference is the enclosure and the rating: an outdoor timer must keep water and dust out of the electronics and the socket. Ask for the protection rating and the operating temperature range, and check that the rating matches the actual installation — under cover, or fully exposed.
What to confirm
Ask about the number of programs, the load rating for the pump or equipment, and whether the timer keeps its schedule through a power cut. Those figures are not stated on this site.