Atomicpunk: Optimistic retro science fiction based on the Space Age. Think The Jetsons.
Biopunk: This genre is about altering genetics and DNA. These stories often take place in the near-future in which humans have been altered or in which human experimentation is common.
Candlepunk: Similar to clockpunk, but darker and with less technology.
Clockpunk: Think Da Vinci’s inventions, but more advanced while. This genre follows the aesthetics and technology of Western civilization during the mid to late middle ages, though sometimes it’s set in the Victorian era.
Cyberpunk: Has advanced technology and often focuses on artificial intelligence and the cyber world. The setting is often near-future rather than far-future. Blade Runner is an example.
Dieselpunk: Based on aesthetics and technology between World War I and World War II, sometimes up until the Cold War.
Decopunk: Ranges from the aesthetics of the 1920’s to the 1950’s. Decopunk aesthetic is heavily based on modernism. Less gritty than dieselpunk.
Elfpunk: Basically urban fantasy, but with common high or epic fantasy creatures put in an urban setting rather than vampires and werewolves.
Nanopunk: Similar to biopunk, but biotechnology is less available and nanotechnology is common.
Sandalpunk: Set in ancient worlds, such as Rome, but with advanced technology.
Splatterpunk: Extremely graphic and contains a lot of gore.
Steampunk: This genre gets its name from the heavy steam-powered technology involved. Aesthetics are based on the Victorian and industrial eras of the Western world, though other cultural elements may be used.
Western Steampunk: Similar to steampunk, but with Western (as in Wild West) aesthetics and settings.
So why are there so many sub genres? For starters, they help agents and publishers get an idea of what they’re in for if you’re going through the traditional publishing route. While bookstores usually just put these genres within science fiction or fantasy, you can still market your book through sub genres to reach a specific group of people who are looking for these genres. However, there are a lot of sub genres, most of which many have not heard of. If you’ve written one of these genres and intend to publish it, the best would be to put it under another name (with the exception of steampunk, cyberpunk, and biopunk). For example, if you have written a candlepunk story, you can propose it as fantasy, alternate historical fiction, or any other genre it may fit in. While atomicpunk is quite common, it’s not well known by that name. If you have written an atompunk story, the best way to market it would be to call it retro science fiction. But what’s the difference between punk genres and historical fiction? The technology is a big difference. It’s usually more advanced for the time it’s modeled after.
The technology is one of the defining aspects of steampunk. It’s the basis for the world you’re writing in. For the typical steampunk story, technology will be (of course) steam powered.
Another defining feature of steampunk is the aesthetics and the characters. Steampunk takes the latter part of the word (punk) to mean the opposition of the mainstream, though that’s not always necessary in your story.
Research jobs common in the Victorian age and add steam to it. Your characters will revolve around their setting and their clothing may be a part of that too.