As an Alternate History novel, A World of Difference is set in an alternate version of the 1990s where, due to the planet that became Mars in our timeline being larger, it has a different composition that makes it suitable for complex life into the present day. This also causes it to have a different color, so it's known as Minerva instead of Mars. Because of this, the Viking missions of the mid-1970s find conclusive evidence of life on Minerva, causing the US and USSR to send a pair of coordinated missions to the planet in order to study the local biosphere. They then find themselves on opposite sides of a war on Minerva, threatening to take the Cold War's proxy wars onto another world.
This book provides examples of :
- Bizarre Alien Biology: Six-section radial symmetry is commonplace on Minerva.
- Bizarre Alien Reproduction: Minerva females (which are referred to as mates) gestate their young six at a time in separate buds, one on each body section. The young connect to the mother's circulatory system for nourishment via their mouths, much like Earth's marsupials attach themselves to a teat in their mother's pouches. When the time comes for the young to be born, the buds on the mother's body split and the young fall off from their attachment points. This process inevitably kills the mother due to excessive hemorrhaging.
- Starfish Aliens: The Minervans possess six-way radial symmetry, with each section having an eye stalk, an arm with three fingers, and a leg. Minervans can point their eyestalks in any direction, speak through breathing pores that appear to be separate from their mouths (which are on top of their bodies pointing upwards), and do not have a defined front or back.
- Values Dissonance: Because of the realities of Minervan reproduction, male dominance in Minervan society is a given. One of the effects is that Minervan mates are never allowed to leave what appoints to a harem.
- Vocal Dissonance: The Minervans, despite using spoken language for communication, are otherwise completely strange looking. Yet their voices are compared to the contralto singing voice of human women. Made even more powerful by the Minervan males possessing such contralto voices.