Wool describes a material; cooling pad describes a marketing category. The latter might be a thin textile, foam or powered system, so the names alone do not create a fair comparison.
Compare the actual construction
A wool-filled topper can change cushioning and bed height. Check its fill amount, cover and manufacturer care instructions. Do not assume it is machine-washable or that wool alone guarantees a particular overnight temperature.
A thin protective pad performs a different job from a thick topper. An active water system performs a different job again. If your mattress already feels right, decide whether adding loft is wanted before considering either a wool or foam topper.
Include cleaning and fit
Measure the combined depth for your sheet and protector. Check whether the topper requires specialist care, spot cleaning or another specific method. Assess handling and return conditions before opening. No comparative temperature testing was performed here, so there is no material-based cooling winner.
See the cooling mattress pad buying guide for manufacturer-linked examples and the differences between fabrics, toppers and powered systems.
See Also
If you are still weighing both sides of this matchup, keep going with How a Cooling Pad May Feel: What to Check at Home, How to Choose a Cooling Mattress Pad for Summer Comfort, and Sleep Humidifier vs. Sleep Sound Machine.
To widen the decision beyond this head-to-head, How to Choose the Right Humidifier Mist Level for Comfort and Best Mattresses for Every Sleep Style provide the broader context.