In most snowshoeing conditions, the pole tip will sink to some extent into the snow and gain purchase at a deeper point underfoot than if you were walking on solid ground. Therefore, poles for snowshoeing should be set at a longer length than trekking. (For a primer on trekking pole adjustment, see
Sticks and Stones: The Pros, Cons, and Uses of Trekking Poles). This is only a concern if you're tall and/or use a pair of shorter trekking poles (lightweight poles and ones marketed for women are usually shorter by several inches).
Shock AbsorbersThis has always struck me as the most overblown benefit/feature of trekking poles. If you believe the hype, the spring-like recoil featured in many trekking poles reduces compressive forces on your hands, wrist, and upper body while going downhill. (I'm skeptical of the claim based on my own experience and have never seen any research to back this up. Plus, the on/off aspect of this feature has consistently been one of the most common issues of poles I've used. But I digress...) Shock absorbers provide no benefit on the loose structure of snow. "Snowshoe" poles never feature them, which also helps keep their cost lower ($50 - $80) than many styles of trekking poles ($50 - $200+).
So the upshot is this: Snowshoe poles are trekking poles. Trekking poles are snowshoe poles.