Formal letters are mainly used for professional or business situation, polite, respectful, purposeful and direct. It should not be overly friendly.Informal letters are usually sent to people who you are close to or know very well. It can be any elements in the letter
Informal letters can be written in first, second or a third person's point of view while formal letters should be written in a third persons view.
Formal letters are mostly written to people who are of a higher authority than us, while informal letters are mostly written to friends, family members or people who you are very close too.
Formal Letters are sent to someone who you are not familiar with and is has a more serious tone.Informal Letters are sent to people whom you are close to and can be written in a very fun and friendly manner.ExampleFormal: Dear Sir,we are very sorry to inform you that you are not selected for the Junior Division Basketball Team and although you may not have made the selection this time, we kindly urge you to continue your own personal training in hope that you may make the Senior Division Basketball Team selection the following year.Informal:Hello Alex,I can't believe that coach didn't choose me for the team! I practiced so hard for it and in the end all my work was for naught. Personally I think that I'm the best player in the team and yet I wasn't selected, I mean you've seen me play, right? Well, looks like Coach is going to lose a few fingers after I'm done with him.
Formal Letters are supposed to be sent to a person whom you either do not know or an acquaintance e.g. your boss, your teacherFormal Letters are supposed to be sent to a person you know very well e.g. your best friend, your family member
Informal letters may contain abbreviated words and are friendly while formal letters require non-abbreviated words and are more serious.
Formal letters are in a more serious tone but informal letters are in a more casual tone.
Formal letters are usually written to someone you're close to but informal letters are written to people of higher rank or writing a letter to request something.
Formal letters is written for people who are in a higher work position then you while informal letter writing is for writing to people we're close to.
Formal letters are written to people with higher authority over you while an informal letter is written to friends/family
Formal letters use cliche phrases while informal letters do not.
FOrmal letters are used towards people of higher authority in a respective field.
Sorry for the late comment.From what I recalled, I have learnt (on that day) the differences and the definition of formal and informal letters:-A formal letter is a piece of written correspondence that is polite and never causal.-An informal letter is quite the opposite, it is a letter which is written in a very casual and friendly tone.Another point that I learnt that day is that it is important to give examples when you are trying to elaborate or explain something to somebody who is finding out about that something from you so that they will understand the topic better.