I use "what3words" as a volunteer in my National Park to locate people or objects in wilderness areas. I used it with another volunteer to report a tree down on a densely wooded trail. Standing side by side we each had two different sets of "what3 words". We moved around staying close together with the same results - different words. When we reported the damage to the National Park Command Center we told him of the difference in words. He said even though the "what3words" covers a 3 square meter area there are often differences between iphone and android phone reportings. While this is a great tool it can be somewhat inaccurate particularly if the location is marked using an iphone and then searched for using an android phone or visa versa. It will get you to the correct general area but that could be more than 3 square meters.