You can separate them from
1. funding stage
2. fund source
3. expertise
4. main source of payment.
Angel: (Smart money angel)
Early, pre VC funding round; Own Money; Personal friend/Industry Expert; Provide contacts and guideline; equity;
VC:
Early to late; Mainly VC fund (other people's money); Provide contacts, strategies and management expertise; Management fee from invested VC fund and a percentage (carrier) from each exited investment.
IB:
Later stage; Mainly money leverage; Provide financial instrument and banking expertise; fee based on deal size.
Each of them servers a different purpose and participates in different stage of a company's lifecycle. You talk to business people in NA. Most of them will tell you the differences.
