What are the differences between the push and pull factors that contribute to urban growth and therefore rural decline?

The distribution of the world's population between urban and rural areas, is evidently changing. Migration patterns and natural decreases (and increases) in population generally create a significant decline in rural areas, and thus encouraging urban growth. In particular, a collective or individual decision to migrate from rural to urban areas is often influenced by existing push and pull factors.
Push factors drive people away from rural areas, as they can make everyday living more difficult, in terms of its economics, political stability and service access, among various other factors. This can be exemplified by the migration patterns from rural Bangladesh to the urban West Bengal, where the Bangladeshi population are driven away by political instability, a lack of industrialisation and a deep economic depression, that in turn creates poor living conditions, health and education services.
Alternatively, pull factors attract people towards urban areas, as they motivate positive change and therefore better living conditions. West Bengal is considerably more developed than Bangladesh, with the sixth-largest state economy in India. Therefore, this creates more job opportunities, which will offer higher (although not necessarily good) wages and job security. In turn, people experience improved access to the facilities required to maintain a better and healthier style of living. However, most importantly, West Bengal offers a level of democracy and religious tolerance that, in Bangladesh, is the root cause of civil conflict.