There is no golden rule, but assume tier-2 cities mayn't have airport, no famous schools, less than 2 or 3 million people living in there. Most of the tier-1 c

There is no golden rule, but assume tier-2 cities mayn't have airport, no famous schools, less than 2 or 3 million people living in there. Most of the tier-1 cities has direct international or national airways connectivity. Tier-3 cities may not even have a single factory, it is hub for 100s villages, has decent bus-connectivity to nearest tier-2 city.