Interesting differences in the numbers.
I'd be a little cautious about the numbers in that World Resources Institute web site, however. For example, it says the 2002 population is 236,000 and projects the population of Belize at 324,000 in 2025.
But the 2000 Belize Census put the 2000 population at 246,000, and the mid-year 2007 population was estimated by the Belize Statistical Institute to be nearly 312,000. The Belize population now is likely already near 320,000, 16 years away from 2025.