Which is an oversimplification of the concept, an often quoted misconception based on the teapot analogy. The fundamental difference is that, like the teapot, both green dragons and blue people are defined within the parameters of our objective perception, the concept (as opposed to any given specificity therein) of God is not...therefore the same is not true of both as you suggest. Any definitive claim as to the existence or non existence of God has equal burden, as each require an attribution of a specific nature with which to define the concept in order to adequately address the question. The problem always arises that by creating that specificity of nature and defining the concept, you also narrow the definition and are only either supporting or opposing that specific interpretation of the term, rather than the objective concept itself. Essentially making either claim subjective and therefore meaningless when asked the question "Does God Exist?"