CEFs and exchange-traded funds (ETFs) are both traded on exchanges, but there are significant differences between them. For starters, CEFs are actively managed, which results in higher trading costs. Most ETFs are designed to track index performance and thus have lower trading fees.
Second, the price of a CEF frequently deviates from its net asset value, and the difference can be significant at times, whereas the price of an ETF is usually within a narrow range of its net asset value.
A CEF can only be bought and sold on an exchange, whereas an ETF can be bought and sold on the open market or by exchanging enough shares for the fund's underlying assets to form something called a "creation unit." Because this second method allows for arbitrage if the fund's price deviates too far from its net asset value, the price of an ETF is never too far from its NAV.