Wera Rodsawang | Moment | Getty ImagesTo the average investor, mutual funds and exchange-traded funds may not seem very different.After all, they are both relatively liquid baskets of stocks, bonds and other assets overseen by professional money managers, and can help investors diversify their portfolios.But there are some key differences that may make one a better financial choice than the other for certain investors, according to experts.How they tradePerhaps the most obvious difference is how investors t ...