How do they compare and contrast bewteen the role of Ophelia and Gertrude?

I'm not sure what you are asking, but I will compare Gertrude and Ophelia for you.  Ophelia is a naive and innocent young girl who is very obedient to her father, whom she loves dearly.  Ophelia is told by her father, in Act 1, sc. 3, to have no more involvement with Hamlet because Hamlet is just using her.  She responds, "I shall obey, my lord."  And she does obey which causes confusion in Hamlet.  In Act 3, sc. 1, when Hamlet talks to Ophelia when she tries to return the "remembrances" he gave her, he is brutal because he doesn't understand why she suddenly shut him out.  Also, the things Hamlet says to her indicate that she is innocent.  The harsh words Hamlet speaks to her again at the play in Act 3, sc. 2, may have helped lead to her insanity when her father dies at Hamlet's hand.  Gertrude is an obedient person, too.  When Claudius asks something of her, such as in Act 3, sc. 1, when he asks her to leave so that he and Polonius can hide and spy on Hamlet and Ophelia, she says, "I shall obey you."  When Hamlet asks her to keep secret from Claudius the fact that he is not insane, in Act 3, sc. 4, Gertrude complies.  At the start of Act 4, Gertrude twice tells Claudius that Hamlet's act of killing Polonius was done from Hamlet's insanity.  Gertrude isn't the innocent flower that Ophelia is, though.  When the ghost of Hamlet's father talks to Hamlet in Act 1, sc. 5, he refers to Claudius as "..that adulterate beast.." implying that Claudius and Gertrude were having an affair when the king was still alive.  Neither Ophelia nor Gertrude is portrayed in a flattering way; both are seemingly without much will power of their own. Both appear to be weak people who are little more than package adornments.