both these words are the same. if there is a difference, Until is more common and probably considered more formal Till - is informal it is found in songs ('Til) don't stop 'til you get enough Until - is formal don't stop until you find him you can also put more stress on until - (show that it is important)

2. a) You won’t get to sleep till your father arrives. (Reference to the entire time-period from when the person says the sentence to the time his father arrives) You won’t get to sleep until your father arrives. (Reference to the time at which his father arrives, say 10 p.m. ) b) Ram will receive benefits till he serves us. Ram will receive benefits until he serves us. 3. a)Until the work is done, I won’t accompany you. (Apply the explanation given in sentence 2) b) Till the work is done, I won’t accompany you. 4. a) He works till 5 p.m. every day. Right. (Explanation: He works the whole day/ from the reporting time to 5 p.m. and not after that.) b) He works until 5 p.m. every day. (Grammatically wrong and makes no sense! This proves that till and until are not interchangeable.) This sentence would work, rather: He works until its 5 p.m., every day. (Explanation: He works till the time its 5 p.m. Here, there is no reference of the time-period before 5p.m.) The difference, probably, must be evident to you by now. Contrary to what most websites concerning English writing and grammar tell, there is a big (though, hardly noticeable) difference between the two words.

They are both used to say when something finishes (Till is more informal): 'He will be working in France till/until next April.' 'He works from morning till/until night.'

REVISE AGAIN : Till- When you use till, you refer to the entire time-period concerned up to the point in time or the point of action Until- When you have to refer to a point in time, and nothing before that —- http://contentcaramel.wordpress.com/2010/04/13/till-and-until-are-different/

There is a slight difference! Till- (meaning) the process (and the time-period, of course!) up to the point of time or action Here, emphasis is on the entire time-period involved or the course of action up to the completion. Until- (meaning) reference to the end-point in time of reference or commencement of an activity Here, emphasis is many a times on the end time or the action mentioned, however, it involves the process too. Where is the difference? Answer: where and what you emphasize upon. a) You will get nothing till you complete the work. (Reference is to the time-period for the completion of the work. Here, reference is to the time during which the work is done and then, completed.) b)You will get nothing until you complete the work. (Reference is to the time at which he completes the work. You will get something only when you have completed the work, and not before that.)