As the global map below indicates the differences seem to be primarily based on language with English speaking countries (U.S., Canada, the U.K. Australia and New Zealand) where references to poverty dominate.
Global Map of Slum, Ghetto, and PovertyThis difference becomes clearer as one zooms into the European regional level where references to ghetto appear to be most prevalent in non-English speaking zones. It is likely that this is tied to ghetto being a more internationalized term than poverty and thus shows up more outside the Anglophone world. But overall one can see that these particular search terms are not used ubiquitously across language groups, highlighting again the importance of using non-linguistic keywords for search, e.g., the number 1, or words that are generally unchanged across space. For example, maps of the names of well know international figures like "paris hilton"  or "osama bin laden" (this is probably the first time those two have been in the same sentence!).
European Map of Slum, Ghetto, and Poverty
Looking at North America therefore is helpful as it represents largely English speaking (apologies to Quebec and Mexico). While it is clear that there are more mentions of poverty than either slum or ghetto there are some intriguing patterns.
Since the term poverty greatly overshadows occurrences of slum or ghetto we also generated a map which just those terms. It is not clear why these differences are here but may simple point to regional linguist preferences with the U.S.
North American Map of Slum and GhettoAgain, this mapping does not signifying a particular economic fortune in any one area but the prevalence of an array of terms associated with economically disadvantaged areas. Still it produces some intriguing patterns.
 Which of course bring up its own problems in the city of Paris and the Hilton Hotel. Maybe we should try Nicole Richie instead?