Although there is some overlapping of programming and opportunity for writers between the two, there is a significant difference between conferences and conventions.
Conventions--such as Bouchercon, mentioned in your post--are FOR the readers/fans while conferences--such as Pennwriters, mentioned by a previous poster--are FOR the writers.
At a convention you're most likely to hear a well-known writer give the "and then I wrote" speech to a roomful of fans. At a conference, that same writer is more likely to give the "here's how I wrote" speech to a roomful of writers and would-be writers.
While attendence at both conferences and conventions can be beneficial to a writer, it's in the writer's best interest to understand the difference and to understand what they should bring to the event (if a speaker or panelist) or take from the event (if an attendee). Having appropriate expectations will play a significant factor in evaluating the experience post-event.
This morning I read a pair of blog posts by a writer assembling his first collection of short stories, where he continually refers to it as an anthology. It isn't. A collection contains the work of a single author. An anthology contains the work of several authors.
I frequently read blog posts and articles by authors who claim to have received galleys of their work, but have probably never seen a galley in their lives. The advent of desktop publishing programs such as Pagemaker, QuarkXPress, and InDesign virtually eliminated the need to produce galleys because these programs allow you to skip that production step and produce page proofs instead.
Why do these errors bother me this morning? Because if we, as writers, can not be trusted to properly use the terminology appropriate for our own industry, how can be be trusted to write about anything else?