Neither definition is the absolute only one but some organizations like to use one or the other to better define their group. The Naturists Society chose that name because was more inclusive and better explained their purpose and the role they expected to fill in society. Another group is the American Association for Nude Recreation, AANR, and it has not adopted the naturists wording and their organization name indicates that the purpose of the association is a bit more narrow in scope. AANR has individual members as well as landed club members. AANR represents clubs and provides educational services for them which includes government relations, and public relations.
So, if you are thinking of trying out the naked way of life, does it matter what you call yourself? If you want to describe yourself to another they might find it easier to understand "nudist" than "naturist". Some even confuse "naturist" with "naturalist" which is a term for one who studies or is concerned with natural world. I suppose one could be a nudist-naturalist though but they are not too common. The bottom line is that it does not matter much what you call yourself. What does matter is that you just do it!
You may be confused about the two main words that describe our naked way of life. Nudism and naturism have much in common but mean different things to those who use them. Naturism seems to describe more of a wholistic way of being nude in that it includes concern for the natural environment and how humans fit into that environment. It implies that we are more natural and comfortable when nude and that we fit easily the natural world.
Nudism seems to explain situations where we are naked either alone or with others. You can be sitting at home or at a nudist resort enjoying the surroundings and maybe not have an understanding or concern for the natural world.
The Naturist Society Guide
World Guide to Nude Beaches and Resorts
Updated guide reviews and gives directions to nude beaches in Europe, Asia, Australia, South America, the United States, Canada, and Mexico, as well as surrounding islands.