Pearls: potential „star“ projects: high probability of success, high expected reward. We would like many of such projects.
Oysters: highly speculative projects: low probability of success, high expected reward. Here the breakthroughs pave the way for solid payoffs.
Bread and butter: simple projects, high probability of success, low expected reward. Often too many of them in the portfolio, consuming substantial ratio of resources.
White elephants: low probability of success, low expected reward; projects that are difficult to kill, often from personal reasons.