[gumby]

Well, with exploratory programming you tend to build up a couple of data structures, add some functions to manipulate them, and then extend out from there. In a more structured way you think up front about a lot more things. In the second you probably doodle some stuff out on the whiteboard or on paper before coding; in the first you probably simply start with an empty buffer type straight into the REPL. There's a time and place for each and certainly not a well-defined dividing line between the two (except in some highly structured UML/TDD processes which may not even exist any more outside aerospace).

For example I talked about the Lisp implementation of the code I'm working on: for deployment it looks like it'll be be an implementation in C++ based on what we end up learning about performance; certain implementation decisions that were particularly good or particularly bad, or that we iterated on several times before settling on something good; and that handles memory management more directly.