Science Fiction?--Flight Behaviour

When I was an elementary school teacher-librarian, I met a boy who had a designation as being on the "autism spectrum." While many other students viewed the library time as "free time", he always posed questions that I really had to think about. His favourite was: "What is the difference between science fiction and fantasy?" I would try to present him with a clear explanation and he would counter with another question. At this point, his classroom teacher, eager to get moving, would put an end to his questioning.

In Flight Behaviour, Barbara Kingsolver deftly weaves science and fiction together. Kingsolver was a biologist and her concern about the effects of global warming and deforestation on the animal population is apparent. In February 2010, there were heavy rains and mudslides in Angangueo, Mexico, one of the principal destinations for the monarch butterflies. Legal and illegal logging activities had removed too many trees from the hillsides. Lives and property were lost in a village largely dependent on butterfly tourism.
This is actually a purse that I bought in Mexico a few years ago.

The novel is set in Feathertown in Tennessee where the Turnbow family are dependent on raising sheep to provide an income to support three generations. Dellarobbia, her husband, Cub, and their two children rely on the elder generation for housing and employment.  A teenage pregnancy and a lack of education have prevented Dellarobbia from leaving this life that she dislikes. As she is climbing a hill to
meet a fantasy lover, she sees the millions of butterflies and her life is transformed.

The ecological theme is important in this novel. The poor people of Appalachia are just as ready to log the hills and to exploit the butterflies as the poor people of Mexico. Many of the environmentalists are too quick to condemn the rural poor who have few resources and little understanding of the situation.

The butterflies' migration is  a metaphor for the choice that each person must make:either to stay in an uncomfortable situation or to leave it. As Dellarobbia learns more about the monarchs, she learns more about herself and about the people around her.

I wonder if my former student ever found a really good answer to his question and I imagine that he is still asking those questions that take up too much valuable class time. I was satisfied with these two explanations by two very knowledgeable authors:
According to SF writer Robert A. Heinlein, "a handy short definition of almost all science fiction might read: realistic speculation about possible future events, based solidly on adequate knowledge of the real world,past and present, and on a thorough understanding of the nature and significance of the scientific method."[5] Rod Serling's stated definition is "fantasy is the impossible made probable. Science Fiction is the improbable made possible."[6]

The monarch butterflies have never spent a winter in Appalachia.