difference, deference

Difference or difference means the quality of being unlike or dissimilar, literally or figuratively--
Can you tell the difference between this picture and the other one?
They are having a difference of opinion.

Deference or deference means yielding to the opinion or will of someone, out of respect , obligation, or practicality--
He always treated his grandmother with deference.
It is important to show deference to the higher-ups if you want to get ahead.

Now that you know that, you can say--
"There's a real difference between showing deference and being a doormat."

Note--"differential" most commonly means the amount of difference between two rates, quantities, or amounts--
The people who work the second shift get a night-shift differential.
Not to be confused with "deferential", meaning respectful--
He was always deferential with the boss, and  his co-workers disliked him for it.
Note # 2--"diffident" means timid, or lacking social or professional confidence--
She though he was shy or diffident, but he was not interested in meeting anyone.
Not to be confused with "different", meaning unlike or dissimilar--
This tastes different. Did you put something different in it?