Deepak - childhood is an abstract noun. So is childhoods. It is the plural noun version. You can use both - but it depends on the context. Most use childhood as a default - as childhoods is rarely used. If you are talking about a universal context - such as childhood in general i.e. all children in the world who mature into adulthood go through childhood - then there is no need to pluralise it. Only if, as you refer, you might be comparing different types of childhood (say between countries or regions) would you be more likely to use childhoods.
Dear Dean, sorry for this late response. In fact, ‘childhood‘ is a cultural construct. It is defined in terms of a time, space and context. So, the universal definition of the ‘child‘ as anyone who is below 18-year of age is meaningless to many communities across the globe. Therefore, there are many forms of ‘childhood’. So ‘childhoods‘ is a more meaningful term than ‘childhood‘ and the little ‘s’ is therefore quite significant.