What caused different cultural identities to develop, despite colonial culture being almost indistinguishable from that of the mother country, even after independence?
First, let's take a look at creoles in Iberian colonies. The divide between the penisulares (white Iberians from the peninsula) and creoles (white Iberians from the Americas and West Indies) was very real. The creoles were considered inferior, and we oppressed by penisulares and the mother nations, and as such developed a separate culture, largely out of necessity. In Anglo colonies, things were a bit different. While assimilation was forced and the colonies held a largely similar culture to the island across the pond, they've been on this vastly different, isolated landscape, surrounded by both Natives and West Africans, their whole lives, thus developing a different culture based on surviving the wilderness and interacting with different cultures
http://www.nps.gov/saan/learn/historyculture/history3spaniards.htm