I think " maine " always uses for past and "mai" use for for present, past as well as future ! but when you use "mai" in past the sentence is past progressive :)

The question can be answered on the basis of Hindi Vyakaran but that'll be too complex to understand to you. So making it simple, I just want to say that when you have done an action you should use there 'Maine' while when the action is in progress you should use 'Main'. Although this is not a perfect answer but hope it will be helpful. Ex: Maine tumhe dekha. Maine apna homework bana liya hai. Main khata hun. Main cigar pita tha.

mainly theres no diffrence , both repersents "i" means the work which i do, nevertheless the its looks strange if we donot use them at right place ,for example: 1. hindi(maine yeh kaam kiya .)english( i did this work) 2.hindi(main yeh kaam karta hun) english( i do this work) . So maine used with past scentense and main used with present scentence . simple ............hahaha yeah...Alok u r write....main also used in future and past sentesnce

mein = i = i am a teacher meine = i am competed my work

in addition to the difference in past and present, there is one more aspect. Maine can only be used if there can be an object to the verb. if there can be no object to the verb, then simply use main, even in past tense. eg. I drove a car. (Car is the object). Main ne Car chalaya I drove (there can be an object, even if not mentioned explicitly) -- Main ne chalaya But ; I slept (no object-- there can be no answer to question-- what did you sleep :) )--- Main soya I ran --- main dauda