What is the difference between "until" and "till"?Are there special situation to use one of them?
For example:
(a) I need to stay here until/till 5pm.
(b) I am planning to stay in the party until/till I get tired.

Question

What is the difference between "until" and "till"?Are there special situation to use one of them?
For example: 
(a) I need to stay here until/till 5pm. 
(b) I am planning to stay in the party until/till I get tired.

Answer

It is just an informal way of saying 'until ' , no difference in meaning !