To some extent the terms are interchangeable. But what are the connotations?
The world is saturated with murder mysteries.
Upstairs, in a fine old house, Mrs Inglethorp dies of strychnine poisoning ...
There are many reasons we might pick up a detective novel. One is obvious and very simple: We know we enjoyed the last one.
Readers believe we are solving one particular mystery, when all along something else entirely has been going on.
From The School of Life
Murder mysteries can be about death and the profound mystery of life itself.
What does it mean to say a mystery novel is literary?
"The most beautiful thing we can experience is the mysterious."
Roland Barthes proposes an erotics of reading. And crime fiction does not come off well.