This is an old argument (which is the genre and which is the sub-genre) that has no clear cut answer. Plus other parts of the world use each term.
I have no easy answer only a personal one. For me there are three distinct groups of fiction in this genre we love: mystery, crime fiction, and thriller. The three are not the same though they may carry some aspects of the other.
I think the split goes back to Hammett, whose fiction was clearly something else. This split is exactly what Chandler was writing about in his essay The Simple Art of Murder.
Look at it this way using modern examples: George Higgins, Elmore Leonard, and James Ellroy do not write mysteries.I just wanted to expand on this slightly since the conversation has moved on. Initially the genre was very mystery based. Then Hammett came along and broke the genre, creating a rift that lasts . What he was doing was so unlike anything that came before (which is part of the reason that he holds a place of importance in the genre) that the genre was forever changed. This change was so fundamental that Raymond Chandler wrote about it in his famous essay The Simple Art of Murder:
I suppose the principal dilemma of the traditional or classic or straight-deductive or logic—and—deduction novel of detection is that for any approach to perfection it demands a combination of qualities not found in the same mind. The cool-headed constructionist does not also come across with lively characters, sharp dialogue, a sense of pace and an acute use of observed detail. The grim logician has as much atmosphere as a drawing-board. The scientific sleuth has a nice new shiny laboratory, but I’m sorry I can’t remember the face. The fellow who can write you a vivid and colorful prose simply won’t be bothered with the coolie labor of breaking down unbreakable alibis. The master of rare knowledge is living psychologically in the age of the hoop skirt. If you know all you should know about ceramics and Egyptian needlework, you don’t know anything at all about the police. If you know that platinum won’t melt under about 2800 degrees F. by itself, but will melt at the glance of a pair of deep blue eyes when put close to a bar of lead, then you don’t know how men make love in the twentieth century. And if you know enough about the elegant flânerie of the pre-war French Riviera to lay your story in that locale, you don’t know that a couple of capsules of barbital small enough to be swallowed will not only not kill a man—they will not even put him to sleep, if he fights against them.
Two-thirds or three-quarters of all the detective stories published still adhere to the formula the giants of this era created, perfected, polished and sold to the world as problems in logic and deduction. These are stern words, but be not alarmed. They are only words.Terminology is an interesting thing though as people freely use different terms in different ways. It's common to see someone refer to reading "schlocky noir mysteries" or other personal identifiers.
In my initial response I named, off the top of my head, three authors who, to me, don't write mysteries. Later comments assured me that those authors absolutely write mysteries.
Here's one of the conclusions I came to. Mystery won the battle and Crime Fiction won the war. Solving something is still central to the genre but the influence of Hammett was so great that he forever pulled the genre in his more realistic direction altering the landscape for generations to come. Hammett is probably the most influential writer in our genre.
What say you DSD'ers?
Currently reading: Submissions, Live By Night by Dennis Lehane
Currently Listening: "Gravel & Wine" by Gin Wigmore