Private Equity investing involves individuals or groups of investors that pool their money together to form a private equity fund. The fund invests directly into a company or it buys out a company and delists it. PE investors usually can commit large sums of money for long periods of time. The long time frame is usually needed for a company turnaround or an IPO.
An angel investor is a wealthy individual who provides capital for a business start-up, usually in exchange for convertible debt or ownership equity. Some angel investors organize themselves into angel groups or angel networks to share research and pool their investment capital.
Angels typically invest their own funds. Angel capital fills the gap in start-up financing between "friends and family" who provide seed funding and venture capital. Angel investment is a common second round of financing for high-growth start-ups.