All three men are accomplished warriors. Banquo and Macbeth are also good friends, and both are tempted by the witches' prophecy. However, Macbeth shows his difference from both men in his overly ambitious nature. He wants to be king, the one in charge, while the other two men are content to be followers.

Macbeth shows the grip of his ambition in act 1, scene 3, when the witches' prophecy about his becoming Thane of Cawdor becomes true. His mind leaps to the idea of realizing the rest of the prophecy by murdering Duncan:

If good, why do I yield to that suggestion

Whose horrid image doth unfix my hair

And make my seated heart knock at my ribs,

Against the use of nature?

In the same scene, Banquo is tempted by the idea of his descendants becoming kings of Scotland but not to the point of taking matters into his own hands. He also believes Macbeth should let his new position as Thane of Cawdor settle in, comparing it to getting used to new clothes, a quote that can be found shortly after the Macbeth quote above.

In act 4, scene 3, Macduff shows his loyalty to Duncan, putting the needs of Scotland ahead of his own ambitions or loyalty to an illegitimate king. This shows his difference from Macbeth. You can find quotes to support that in his dialogue in the scene with Malcolm.

Of course, Macbeth is loyal to Duncan until his own desire for power becomes too great, so we have to hope Macduff is a better person. We also must hope that as king Malcolm will be wiser than his father in judging people. This seems to be the case, thanfully, given how he tests Macduff's loyalty.

The characters of Macbeth and Macduff actually have a number of similarities between them, which mark them out as being separate from Banquo, who is actually presented as a somewhat more sensitive character. Note how Macbeth is introduced in Act I scene 2 before the audience even meets him:

For brave Macbeth--well he deserves that name!--

Disdaining fortune, with his brandished steel

Which smoked with bloody execution...

From the very start of this play the audience associates Macbeth with slightly over-zealous pugnacity, as is shown through this description, coupled with the deal of how he "unseamed" the traitorous Macdonald "from the nave to th'chops." In a similar way, Macduff, although a soldier of honour (and in this sense completely unlike Macbeth), shows his violence through his bloodthirsty pursuit of Macbeth in Act V:

My voice is in my sword, though bloodier villain

Than terms can give thee out.

The audience is shown that Macduff is consumed with his desire for revenge and willing to commit murder in order to achieve that goal, which strikes an interesting similarity between his character and Macbeth's character. Banquo, however, is shown to be of a very different ilk. He is shown to be different from Macbeth in the way he responds to the witches as shown in Act I scene 3. He, rather than act on his suspicions of Macbeth's treachery like Macduff, resolves to quietly flee and escape. He is presented as rather a weak character compared to the machinations of Macbeth and the strident zealous desire for revenge of Macduff.