[mamonster]

Slight simplification: Bonds aren't like stocks. For a given company, there is typically 1 common stock issue(perhaps multiple share classes FAANG-style for voting or maybe issued on different exchanges), maybe a preferred issue and then like 10+ different types of bonds, which are very different(typically, the shittier the company's financial position the bigger the difference between the senior/secured and the junior/subordinated debt).

Senior debt is basically either directly secured by specific assets/collateral or is the first to get paid out in case of a default. Junior debt is typically unsecured(no specific collateral) and goes after other, senior unsecured debt has been paid off.

When you hear about a company's credit rating, its usually the rating of the senior unsecured(so the "safest" bonds that aren't secured by specific assets).

[rsynnott]

_Some_ stocks, typically in private VC-funded companies, are like this too, FWIW.