What’s the difference between a form and a pop-up form?

Experience — forms are inbound. Pop-up forms are outbound.
Location — forms only exist on landing pages. Pop-up forms only exist on pillar pages.
Forms can be used in the awareness, consideration, and decision stages of the buyer’s journey. Pop-up forms are only used in the decision stage of the buyer’s journey.
Experience — pop-up forms are a CTA, landing page, and thank you page all in one. Forms are part of a larger conversion path.