How much power do words really have? In this play, Shakespeare pits the power of language against the power of action. On the one hand, Richard more or less believes that his speech is power. In one sense, he's right: Richard can end a man's life just by banishing him or ordering a murder. So language is powerful, in the political sense. Later, once Richard is no longer king and his words don't have any political power, he manages to make his language forceful in a different sense: his words are often quite moving and poetic.
Henry Bolingbroke, on the other hand, makes it clear that he doesn't think much of language. Unlike Richard (who describes his fall from grace so poetically that we almost forget he was a bad king), Henry isn't a good storyteller. He thinks action is far more important than language, which is why he's so great at seizing opportunities and creating situations that will give him power.
Whereas Henry Bolingbroke is bad with words and seems to think language is less important than action, Richard is a gifted speaker who doesn't understand that speech isn't enough.
One of the conflicts in the play is who gets to tell the story of England: Richard or Henry.