Please detail the contrast between Rosencrantz and Guildenstern in "Hamlet".
See, but that's the thing - there is no contrast between these two characters. Although two are included, they serve a singular purpose in the story and are not only always seen together but are always in agreement. The two serve the purpose of demonstrating blind loyalty. The person that they contrast with is Hamlet himself.
Hamlet has been commanded by the ghost of his father to avenge the murder committed by his uncle. Hamlet hesitates. He has a clear personal reason - his own anger and guilt - and a reason of duty - obeying his father. However, he can not manage to bring himself to commit violence or murder willingly. The one time he reacts with speeds and without conscious choice, he mistakenly kills Polonius. Hamlet is plagued by his own morality, as well as his intelligence.
Rosencrantz and Guildenstern are not like this. They are happy to receive on order, because all they want to do is follow orders:
ROSENCRANTZ: Both your Majesties
Might, by the sovereign power you have of us,
Put your dread pleasures more into command
Than to entreaty.(Act II, scene ii, line 30)
They do not question the morality of anything Claudius tells them to do, from spying on their friend Hamlet to arranging for Hamlet's murder. Shakespeare uses R and G to show that this extreme example of loyalty is dangerous and often immoral - which is why R and G seem so mindless and why they are killed off in the end.