The imperfect analogy I've used is the comparison between paints and pencils. They perform similar general functions (placing something on a media) and even use

The imperfect analogy I've used is the comparison between paints and pencils. They perform similar general functions (placing something on a media) and even use a similar set of tools (a long stick held in the hand). But the end result and even the goal could be totally different (I may want to hang a painting on a wall in a frame and I may want my pencil drawings to be reproduced a book). It's not perfect, but it helps non-users (i.e. managers) understand that one tool does not fit all.