The trade-offs between buying from a builder and buying from an owner.
You choose from plans and pay in stages, usually for a home that is not finished.
You buy what exists, from the person who lives in it.
If you need to move soon, resale gets you in sooner. If you can wait, want a particular layout or are buying as an investment in a growing area, a new project may fit. The prices of the two in the same locality are on that locality's page on this site.
This guide is general information, not legal, tax or financial advice. Rules differ between states and change over time, so confirm the details that matter to you with a qualified professional or the authority concerned before you act.