In what ways are Othello and Desdemona alike and different?

A major point similarity between both characters is that
they are in love with one another.  Othello and Desdemona possess a love for each other
in which they believe at the start of their relationship.  Whether or not, this actually
is love is another issue, but they both believe in the authenticity of their emotions
and this represents a point of similarity between them.  Another shared distinction is
that they are both renegades, to a certain extent in that they operate outside the
sphere of accepted society.  Othello is both a warrior and a man of color and a man of
different ethnicity in being a Moor, making him uniquely different than most of the
"insiders" in Venetian society.  While he might have been granted title and wealth, for
all practical purposes, he is still a relative outsider.  It is here that Desdemona fits
in that she breaks ties with her father and family for Othello, willingly running away
with him.   This makes her an outsider in both her attitude and in that her father
disowns her as a result.  The most distinct difference between them is that Desdemona
possesses much more confidence and a sense of the self assured as a result of her
actions.  She holds much more in way of internal confidence in what she does and who she
is than Othello does.  The Moor is always the victim of doubt and this is what makes him
completely susceptible to Iago's machinations.  Another point of difference would be in
their relative power.  Othello has power.  While he might become victim to Iago, he is
never isolated and cut off from others.  He has options.  Desdemona does not.  As a
result of her running away with Othello, she placed all of her lot in this action.  When
the relationship turns sour, she has no one else and no real source of power to check
the encroaching abuse.  It is here where both are different, as
well.