Oxfam, like many others, are intentionally trying to obfuscate the difference between wealth inequality and income inequality in order to confuse the naive and ignorant.  They are using a meaningless statistic on wealth inequality in order to make an argument in favour of something they hope will reduce income inequality.

Why?  Because if they used statistics on income inequality they would find that income inequality actually hasn't changed by any meaningful amount in Canada in more than 15 years now.