In the small, all paradigms are the same.

    print "Hello World"

with suitable syntax tweaks, is imperative, functional (that code works in Haskell), declarative, and logical (Prolog has a print). Or, more accurately, is simply too small to be usefully discussed in this context. You have to pick something larger to talk about.

Suppose the langauge has a built-in printf() and sleep() function.

You could say main=printf("Hello World"), which declares that your program is equivalent to the action of printing "Hello World".

You could also say that main=sleep(1), which declares that your program is equivent to the program sleep(1).

You can also say that main=sleep(1) >> printf("Hello World"), which says that your program is equivent to the program that sleeps for a second, then prints "Hello World".

You can even create syntactic sugar around the concatenation operator, so it looks like you are programming in an imperative language.

If the concatenation operator happens to be over-loadable, you can do a lot of neat stuff with it. Even if it isn't, you can define common control flow operations (such as for loops) at the language level, which means that you can just as easily define new control flow operations that the language designers didn't think of.

Using HTML? It's a declarative language.

It's nice to have the data/declarative notion of an instruction. It's even nicer to have this notion be exactly the same notion by which you cause effects via your language. This means that all effectual code you encounter can, at least in principle, be analyzed as a declarative data structure.