Investment advisor/adviser does the same jog as investment consultant does. But investment advisor is a term used by the Securities and Exchange Commission (SEC). So usually investment advisor refers to a company or individual who is registered by the SEC. It‘s the only difference between advisor and consultant, which disappears if the advisor is not registered by the SEC (also it may be because of small size).
Anyhow, investment consultant or adviser performs similarly. If we talk about individuals, theoretically, investment consultant or adviser should only give recommendations for the client but not to take any decision on himself. He should give a useful material about stocks and other securities, comments on it, share some investing ideas, cover ant present the situation of financial markets and tell about best brokerage services. However, the real consultant should not do what investment manager does: makes an investment decisions what securities and when to buy or to sell, makes trading transactions for the client. But in practice all these functions are mixed up and depends on the company and it's culture.