Because in both the cases, the warm water/ increase in temperature is seen on the east side of Africa. Does not they mean that they carry rain bearing clouds from east of Africa to India, resulting in flood like situation in India. Do they differ in any other way, please let me know if I got them wrong?
The Indian Ocean dipole is essentially a measure of the difference in sea surface temperatures between the western and eastern Indian Ocean.
The El Nino and La Nina are the opposite phases of the El Nino Southern Oscillation cycle that occurs in the Pacific Ocean.
The only similarity with the Indian Ocean dipole, is that the difference between the sea surface temperature between the central western Pacific Ocean & central eastern Pacific Ocean are measured.