One of the more obvious differences you see between most elite pool and open water swimmers is the arm recovery above the water. We admire the elite pool swimmer's arm recovery above the water (first photo below) with that classic high elbow and the hand just clearing the surface of the water but when it comes to open water swimming this is not ideal.
In open water the conditions are not always flat like in the pool, there is wave chop created by the mass of swimmers, wind chop/waves, ocean swells and that's not taking into account other swimmers trying to be in the same space as you bumping and banging into you. Conditions are very rarely perfect when you are open water swimming so a modified arm recovery is beneficial. A couple of other arm recovery options from the classic one is an open arm as in photo 2 below or the straight arm (windmill) style as in photo 3. If you watch any of the recent TV coverage of the triathlons at the Commonwealth Games these are the styles you will see. They might not look pretty but it's not about being pretty but being effective and if you were to see the underwater coverage of these elite triathletes/open water swimmers they still have excellent catch and pull throughs.
With these 2 arm recoveries your hands are clearing the waves as well as that someone swimming directly beside you. Another benefit is that if you are wearing a wetsuit where the neoprene can cause restriction of movement through the shoulders these styles are less restricted than the classic recovery so you won't fatigue as quickly through the shoulders.