A stock is a partial ownership of a business with no promise of anything than your share of what all the owners get if they is something.

A bond is a promise of interest of and repayment of principal in a priority basis.

For the most part ownership assets such as stock give portfolios their dynamism in their upside potential but at the cost of being uncertain an having significant downside potential.

Lending assets such as bonds have a fixed promise which is dependable but limited in its upside.