The Australian Association of Angel Investors uses the terminology as follows:
Angel means an individual person investing his/her own money and time in a company other than by way of a public stock exchange.
Active Angels have discretionary funds, have invested (some more than once)
Solo Angels invest without reference to other Angels (historical norm)
Angel Groups are a collection of Angels who review and evaluate deals together but, the decision to invest is made individually
Angel Syndicate is the subset of Angels from one or more groups who decide to invest in a particular deal (typically through an aggregating vehicle, e.g. unit trust)
Angel Fund is a pooling of investment funds from Angels and possibly from other investors. The fund makes Angel stage/style investments with the decisions and administration of the fund being undertaken by appointed fund managers (preferably professionals but, not always).
Side-Car Fund is usually a pooling of funds from members of an Angel group. The fund typically co-invests with group deals according to a formula that details how many members and how much money must be committed to trigger a co-investment as well as characterising the matching ratio and investment cap. The fund is typically managed by volunteer group members.
Co-Investment Fund is similar to a Side Car Fund but, usually is a pooling of funds from investors other than Angels.
Virgin Angels have discretionary funds, decided to invest but, have not yet invested.
Latent Angels have discretionary funds, have not decided to invest.
The MIT Entrepreneurship Center in the USA identifies four types of Angel investors:
Guardian Angels Bring both entrepreneurial and industry expertise. Many have been successful entrepreneurs in the same sector as the new companies in which they invest.
Entrepreneur Angels Have experience starting companies but come from different industry sectors.
Operational Angels Offer industry expertise – often from experience working for large, established companies – but may lack first-hand experience with the travails of a start-up.
Financial Angels Typically invest purely for a financial return.
In Melbourne Angels we have a healthy mix of each of these types of investors. This diversity improves the quality of our investment decisions and strengthens our ability to assist our portfolio companies to succeed.