Wealth Gap: This is the unequal distribution of assets among residents; it’s like comparing who has more toys in a playground - some kids have loads, others have few or none.
Poverty Line: This is an official measure that defines those individuals or families considered impoverished - not meeting basic needs for food, shelter etc.; imagine it as a high jump bar set by society - those unable to cross it are deemed 'poor'.
Economic Mobility: This is the ability of an individual or family to improve (or lower) their economic status—usually measured in income; consider this as climbing up (or sliding down) on life's ladder based on your financial situation.