For a fascinating description of mystery genres, see Books ‘n’ Bytes discussion.

I think they mix genre (all of its wonderful permutations) with archetypes and motifs, setting, character… But it is an interesting discussion.

I especially like Camille’s (incredibly simplified) list of mystery types:

In the old days, publishers and critics classed mysteries in four (later five) sub-genres.
1) Ratiocinative (Puzzler, Whodunnit or “Classic”), where the emphasis was on the clues and the puzzle (Holmes, Ellery Queen, Charlie Chan).
2) Cozy, overlaps with the above, but specifically has a domestic setting, and an amateur detective — and it’s about the people more than the clues. Agatha Christie is the prime example here.
3) Hard-boiled–which may or may not involve a puzzle–has a private detective or criminal as the main character, and is about the seedier side of life. It relates to much pulp fiction and Film Noir. Dashiel Hammett and Raymond Chandler are the major examples here.
4) Police Procedural, which also may or may not involve a puzzle, is more about the police themselves — and may focus tightly on the case (think the TV show Law and Order) or more broadly on the melodrama of their lives (Hill Street Blues or LAPD Blue). Thriller is another sub-category–where the emphasis is on danger and suspense rather than the crime, sometimes a variation of Cozy (Woman in Jepardy) or Hard-boiled (Criminal stories).

If you don’t know what a cosy is, it is defined earlier by David and Vicki Ball as:

Cozy: There is a LOT of discussion on what does/does not constitute a cozy.

American Cozy: see Classic Cozy, but may include broader, harder-edged activity in a larger community.

Classic Cozy: small enclosed community, sex or violence off-stage, amateur sleuth, eccentric characters, a puzzle solved.

Potato Chip book: a good, quick, light read that won’t keep you awake at night.

I personally prefer classic cozies and potato chip books. Robin Paige’s works are classic, so are Susan Wittig Albert’s.

But I also like the Puzzlers (ratio what?), especially Holmes and those like him.