Final answer:
The main difference between Series 6 and Series 7 licenses is that Series 7 allows the selling of all types of securities, whereas Series 6 is limited to mutual funds, variable annuities, and variable life insurance.
Step-by-step explanation:
The fundamental difference between a Series 6 and a Series 7 license is that with a Series 7 license, the registered representative may sell all types of securities including corporate, municipal, US government securities, options, direct participation programs, investment company products, and variable contracts.
In contrast, a representative with a Series 6 license is limited to sales involving mutual funds, variable annuities, and variable life insurance products. These licenses are required for professionals in the investment industry and are a result of regulations to ensure that registered representatives have the requisite knowledge to sell securities and protect investors.