Shares outstanding is what exists today; float is what actually trades; diluted shares add the claims that will exist — unvested RSUs, in-the-money options, convertible notes. Market cap is price times diluted shares, the price of the equity only.
Enterprise value adds debt, capitalised leases, preferreds and minorities and subtracts cash: the price of the whole business, independent of how it is financed. A net-cash company has EV below market cap; a leveraged one has EV far above it, which is why cheap-looking equity in a levered business is often a call option on solvency. On EV $10bn made of $2bn equity and $8bn net debt, a 20% fall in business value is a 100% loss on the equity.
Track share count over five to ten years, then compare cumulative buyback spend with cumulative stock-based compensation. If a company buys back stock only to offset SBC, that buyback is not a return of capital — it is payroll.
Educational, not investment advice.