Full service broker - A full service broker will offer you his expert advice, views, recommendations and research. A full service broker also offers an extensive varieties of financial products and of course charges higher fees or commissions
Discount broker - Discount brokers do not offer advice, recommendations etc. They simply carry out the stock trading process according to your instructions, nothing more nothing less.
Online Stock Brokers - with Online stock brokers platform it is easy for everybody to learn how to trade, invest etc with little o no commissions. The downside is you have to carry out the trading alone, thereby leading to lose of money by inexpert investors/traders