"Differ to", "differ with" or "differ from"

Solution 1:

Macmillan Dictionary gives a definition of "differ" together with good examples:

1. to be different from something else

   differ in: The two animals come from the same family but differ in body shape and breeding habits.

   differ from: English differs from Spanish in that it is not pronounced as it is written.

   differ widely/significantly/greatly (=be very different): Laws on pollution differ widely from one country to another.

   differ from something to something: The techniques used differ from company to company.

2. to disagree with someone about a subject

   differ on/over: Experts differ on the causes of the disease.

   opinions/views differ: Opinions differ as to the likely winner of the tournament.

   differ with: Baker also differed with members of Congress over this issue.

   beg to differ (=disagree): I beg to differ with you a bit there.

Solution 2:

Mehper's answer is comprehensive, but if you want to settle on one I would recommend "differ from". The thing to remember is that we are talking about the opposite of being similar to something. Since "to" and "from" are opposites, it's logical that the opposite of "(be) similar to" is "differ(ent) from".

I know that English isn't always logical but in this case it conforms nicely. As an aside, a real pet hate of mine is "different than" - it makes me wince every time I see or hear it!