GMO versus GRO
GMO = Genetically Modified Organism
A plant or animal that is genetically characterized well enough by scientists to have genes inserted or changed. Modern GMOs are completely sequenced - we can find out what is in them.
Some GMOs ("roundup ready") are designed for herbicide resistance, but that does not mean they are actually laden with artificial herbicides. Many plants (like soybeans) make their own "natural" pesticides - and humans are among the "pests" these plants evolved to injure. Rule of thumb - if a plant is valuable as protein, it evolved some mechanism to protect that protein from us.
GRO = Genetically Random Organism
A plant or animal with uncertain genetic makeup. GRO food plants in mass agriculture often usually highly selected from random genetic variations, often produced by chemical or radioactive mutagens during the twentieth century. May have random genes from other species inserted by retroviruses, if those viruses afflict both species.
AFAIKS, the main difference between these is that GRO plants are less understood by scientists. When I see "non-GMO" food labels, I see the proud proclamation "I hate genetic/scientific knowledge". That said, I would like to actually have the knowledge, and would prefer to have the genetic sequences and SNPs available (perhaps on a website) for everything I eat, regardless of whether it is GMO or GRO.
I wonder if religious creationists are more likely to avoid GMO foods?