The most common meanings of the word "yield" in an investment context are:
Although they are superficially similar measures, there are important differences between them.
The first is that yield to maturity is a measure of total return on an investment. On the other hand flat yield and dividend yield are measures of the income at a point in time relative to the price.
Dividends are a very different income stream from interest. Bond yields are usually either fixed or floating and will be paid unless the issuer is in serious financial difficulty.
Dividend yields depend on company profits and dividend policy. This usually means that dividend will grow. It also means that they tend to be far more risky than interest payments on bonds. This is why a yield gap exists.