Income and consumption are two different observable outcomes, over which we measure inequality of opportunities.
Income is “disposable household income”, i.e. the sum of all incomes going to a household over a certain period, minus taxes.
Consumption is “household expenditure”, i.e. the sum of all monetary outflows in the household (e.g. food, clothes, energy, transportation etc.) over a period of time.
While income is our preferred outcome, developing countries often have issues when collecting this information as it fluctuates a lot and can come from many different sources. So, consumption is often used to measure wellbeing – and inequality – in many of those countries.