Ann: Magellan Global Fund Partnership Offer Opens, page-6

I have the same questions and found some info.

Why can closed-end funds sell at prices that differ from net value while open-end funds do not?
Close-end funds trade on the open market and are thus subject to market pricing.
Open-end funds are sold by the mutual fund and must reflect the NAV of the investments

What are some differences between a unit investment trust and a closed-end fund?
A unit investment trust is an unmanaged mutual fund. Its portfolio is fixed and does not change due to asset trades,
as does a close-end fund.Investors who wish to liquidate their holdings of a unit investment trust may sell the shares back to the trustee for net asset value, while a close-end fund is traded on the open market.

What are some comparative advantages to investing your assets in a Unit-investment Trusts?
A unit investment trust offers low costs and stable portfolios. Since they do not change their portfolios, investors know exactly what they own. They are better suited to sophisticated investors.

What are some comparative advantages to investing your assets in a Open-End Mutual Fund?
Open-end mutual funds offer higher levels of service to investors. The investors do not have any administrative burdens and their money is actively managed. These are better suited for less knowledgeable investors.