When you are talking about distance, further and farther might mean the same but when you look into it, you will realize that further is not only a term used for distance. It can be used to pertain to other things. For example, when you say, “I believe that you will go further in life.”
This means that you believe in the person and you think that the person will achieve more in the long run. You can also use it to describe other things that are considered to be abstract like time. When you use farther, you may refer to something that you can grasp.
Further and farther are two words which might literally have the same meaning when you are talking about distance. When you look at the two words, the only difference you will first point out, is the fact that the second letter of the two words is not the same. Most times, people get confused as to when and how to use the two words. Although, both further and farther might be having the same meaning because they are two adverb words that talk about distance, there are still many differences between them.
The first notable difference between further and farther is that, further can be used in a lot of ways because it has different meaning, and anytime it is used in relation to distance, it is usually used for abstract things like time. Farther, on the other hand, is used to describe distance in space or distance between places. Anytime farther is used, it is usually about something physical, unlike further, which seems abstract. Also, further is at times used as a verb, but you can't use farther as a verb.