Essentially, the similarities between the deaths of Duncan, his guards, Banquo and Macduff'f family, as seen in William Shakespeare's Macbeth, have one resounding tie: they all lose their lives based upon Macbeth's ambition.
Duncan and his guards die for one reason: Macbeth desires the crown. Since hearing the prophecy of the witches, Macbeth's ambitious nature has compounded. He will no longer allow fate to make the moves:
If chance will have me king, why, chancemay crown meWithout my stir.
The guards die so that Macbeth can place blame on someone other than himself. Duncan dies so that Macbeth can have the throne.
As for Banquo's and Macduff's family, their murders are a part of Macbeth's plan to keep the throne. Macbeth knows that Banquo is a threat based upon the fact that he witnessed the prophecy. Known by readers but not by Macbeth, Banquo does believe that Macbeth may have had something to do with Duncan's death.
Thou hast it now: King, Cawdor, Glamis, all, As the weird women promised, and I fear Thou play'dst most foully for't.
Also, Macbeth fears that another part of the prophecy will come true: Banquo's sons will be kings. By this, Macbeth believes that he will lose the throne to Banquo's sons. Therefore, by trying to murder Fleance, and murdering Banquo, the likeliness of the prophecy coming true is lessened.
Like Banquo's murder, the murder of the Macduff family is meant to insure Macbeth keeps the crown. He believes that Macduff will try to kill him (again foreseen by the prophetic witches and the apparitions).
Macbeth! Macbeth! Macbeth! Beware Macduff; Beware the Thane of Fife. Dismiss me. Enough.
Therefore, Macbeth sends the murderers to kill Macduff (unaware that he has fled). Instead, the murderers kill Macduff's family.
Sinful Macduff, They were all struck for thee! Naught that I am, Not for their own demerits, but for mine, Fell slaughter on their souls. Heaven rest them now!
In the end, all of the characters (Duncan, his guards, Banquo, and Macduff's family) are murdered to insure the throne for Macbeth.