I think “in poverty” is a subset of, not an equivalent to, “low income.”
ETA:
From the linked report:
NCCP defines a poor household as one where incomes are below the federal poverty threshold (i.e., $24,036 for a family of four with two children in 2015). Families with earnings less than twice the poverty threshold are considered low income and include poor families (i.e., $48,072 for a family of four with two children in 2015).
