What is the difference between blank verse and rhymed verse ? And who uses blank verse / rhymed verse in Hamlet?I was told that aristocracy used...

Blank verse is poetry that does not use rhymed iambic
pentameter (a line of ten syllables with five stresses and no rhyme). This is typical of
Shakespeare's works, although he was less strict with this structure as time
passed.

In fact, Shakespeare does not distinguish between
the classes in this manner. Laertes's speech to Ophelia in Act I, Scene III, is written
in blank verse.

Hamlet, on the other hand, speaks primarily
in prose. Often he appears to be insane, and in these situations, Shakespeare abandoned
verse altogether, likely because it has too much structure to support or display
insanity in his characters.

However, when Hamlet is
speaking seriously, or when romance is involved, Shakespeare reverts to structured
rhymed verse. It is also used to distinguish various things int he script--for instance,
when the actors enter and put on the play within the play, Shakespeare utilized rhymed
verse. This helped make it obvious to the reader that the "Mousetrap" was different from
Hamlet, so that confusion would not overcome. Further, this casts a
horrifying hint of dark humor over the entire situation; rhymed verse often sounds
sing-song, reminiscent of nursery rhymes, and highlights high tension as well as the
conflicting ridiculous nature of the trap.