hmmm... i think "Yours sincerely" is properly used in social correspondence.If you address the person by name (i.e. if they are known to you socially) you write "your sincerely". we would use "sincerely" when a name of the reciever is mentioned at the beginning. and "Yours Truly" we use it in personal correspondence to someone we don't know well. If they are not know to you socially you write this (can be your frnd's frnd). This is the standard way to end a personal letter. at last i think the same thing in these both is "Yours Truly" or "Yours Sincerely" is for someone you don't know at all. i hope it will help you. ^-^

Hi tricson I would say they are synonymous; I would use 'yours sincerely' myself, because I think 'yours truly' is slightly more personal not appropriate for a formal letter.

Hello Tricson, Linguistically truly means: telling the truth ,sincerely : without any deception or exaggeration to impress or please. In that sense they could reflect the same meaning and be used interchangeably to close a letter of correspondence mostly a formal one addressing people you are doing business with or people you hardly know. Different countries may be accustomed to use the one or the other,but profoundly there is no difference. As previously mentioned by others they are not used in informal correspondence between siblings or close friends,that would sound weird .

like sonnia says, any use of "yours" would be more informal. don't use "yours..." in a business letter, especially in a cover letter for job applications. you don't quite belong to the company, institution, organization quite yet, so don't make it sound like you are. :P

The rule in the UK used to be that if you start a letter with Dear Sir/Madam, you end it with Yours Faithfully, and if you start with Dear Mr X you end it with Yours Sincerely. I believe that in the US Yours Truly was used instead of Yours Faithfully, but perhaps someone else can confirm that. These rules are for quite formal business correspondence, but if you follow them you are unlikely to offend anyone. If you are writing to a friend, or sending an email, there are other more informal ways to finish, such as "kind regards" or "best wishes".