Provisional vs non-provisional patent: what's the difference?

These are both US filing formats: a provisional application secures a filing date and 12 months of "patent pending" status without starting examination, while a non-provisional application is the formal filing that actually enters examination and can result in a granted patent. A provisional must be followed by a non-provisional within 12 months or the priority date is lost; outside the US, a first national filing plus the Paris Convention's 12-month priority window works the same way.