Wealth is just saved/residual income. ie at some point it is income. ie at some point it can be caught by income tax provisions.
I'd say wealth is your assets (net) at any point in time, e.g real estate increases & inflation, aka non cash items.
Investments (shares, property, art,gold,cars) held rather than traded.
Income is usually cash or benefits.
It is not unusual to see headlines claiming a billionaire made or lost $zillions based on the value of shares or minerals rising or falling without a dollar changing hands, aka notional gain/loss.