Lakhs and crores are units of the Indian numbering system commonly used throughout the Indian subcontinent. Millions, on the other hand, are used internationally and are equivalent to "thousands of thousands" and are grouped accordingly when represented numerically. For example, 2 million would be represented as 2,000,000. It can also be abbreviated to 2M.
1 million is equivalent to 10 lakhs and 100 lakhs is equal to 1 crore.