Apple REIT is a publicly traded, non-listed REIT, not a private REIT.
These unlisted REITs are generally sold to investor's through middlemen like David Lerner, usually through 'free' seminars. What these unlisted's pitch is that the investor does not need to be concerned about market changes in share prices....which are 'held fixed' at some predetermined price per unit. The unlisted REIT promises to pay a fixed dividend that may or may not rise in future years. Once purchased, the units have virtually no market and may only be redeemed through the issuer, often limited to a few % of outstanding shares per year either at the issue price or a discounted price.
In other words, once you buy units, you have no flexibility, little if any growth and usually a fixed, bond-like dividend payment. Some units mature at a historic date, some may be converted to publicly traded shares if the company decides to list its shares on an exchange at some future date, and some never mature and forever carry surrender charges.
I have never heard of a knowledgable investor electively purchasing these units. They are typically sold to retirees who simply don't know any better.
If your mother is considering REIT investments, I would definitely stick with the publicly traded variety, which have provided cosistent and growing returns over the past 15 years and offer full liquidity.
A good place you might want to visit is The Motely Fool's 'REIT and Real Estate' discussion forum.
BruceM