-- my attempt:
Imperative defines the order and semantics of each step.
Declarative defines the prerequisites and intent of each step.
The algorithms each can implement are equivalent.
https://existentialtype.wordpress.com/2013/07/18/what-if-any...
Semantic is another word that is hard to define.
I find imperative better for expressing state machines. I find declarative better for backtracking.
You can write a state machine with just a loop, an assignable, and conditions. Writing state in prolog is irritating.
Similarly declarative programming is strictly secondary to imperative. It is a limited form of imperative that codifies some good patterns and turns them into a structure. But it also makes it hard or impossible not to use these patterns.