They are different.

Farther refers to length or distance. It is the comparative form of the word far when referring to distance.

Further means “to a greater degree,” “additional,” or “additionally.” It refers to time or amount. It is the comparative form of the word far when meaning “much.”

Difference Between Further And Farther

far left and far right are therms from an ancient world. There are 2 big sorts of political point-of-views: economical and individual, the differences are the next: You can have a very left economy and give a lot of individual freedom, the ideologies that support this is socialism. They are for a lot of government control on the economy (nationalizations, heavier taxes), but they also like to give a lot of personal freedom (trade unions, freedom of speech, …). Famous examples are: Chavez of Venezuela (this is highly discussable, I know), Trotsky, Lenin and Nader. A verly left economy can also be a totalitary society, examples: Soviet-Union under Stalis, Cuba of Fidel, … The economy here is in hands of the government, but there is no free speech and no freedom of the presses. A right-wing economy and individual freedom is called libertanianism. A good example seems to be the founding fathers of the USA (George Washington, …) and also the US liberal parties. If you want everything on the right, then you get Bush, Reagan, … They offer tax cuts to big companies for example. But they don’t give a lot of personal freedoms (with this I mean: no abortion, not much stem-call research, …) So you see that the part of the political spectrum that hates Bush can’t immediately be labeled “far-left.” There are many other gradations.

Farther–

Farther shows a relation to physical distance. If you can replace the word farther with “more miles” then you have done it correctly.

* Our car drove farther than I thought it would on one tank of gas.

* I wanted to run farther, but I became too exhausted.

* Our house is farther away from the restaurant than yours.

Further–

Further relates to metaphorical distance or depth. It is a time, degree, or quantity. It is also another way of saying “additional”.

* I asked that there be further discussion on the matter.

* I need to look further into the logistics of moving farther from my office building.

* I hope that gas prices drop further for our road trip vacation.

Some authorities (like the Associated Press) insist on “farther” to refer to physical distance and on “further” to refer to an extent of time or degree, but others treat the two words as interchangeable except for insisting on “further” for “in addition,” and “moreover.” You’ll always be safe in making the distinction; some people get really testy about this.

Further means additional information. Like: You need to wash the car; furthermore, you also have to clean the inside.

Farther is distance. He ran farther than I did.

Farther refers to physical distance and further refers to an extension of time or degree.

It’s Farther which refers to distance.

I do not want to walk much farther.

“Further” refers to time or amount.

What? Where? When? How? Who? Why?

I have always thought they were totally interchangeable. Fewer people use the word ‘farther’. I have the feeling it is much older thatn ‘further’, which at one time almost replaced ‘farther’. (at least in the UK)

Further: An Adjective for additional, extra, more.

Farther: An Adverb for greater distance or extent.

The difference is beyond the ‘u’ & ‘a’