What distinguishes a 'failed star' like a brown dwarf from Jupiter, according to the text's distinction between object types?

Answer

A brown dwarf failed to become a star, whereas Jupiter never even attempted to meet the stellar criterion.

The text emphasizes that brown dwarfs sit in the transition zone where stellar ignition was narrowly missed, while Jupiter is simply too light to ever meet the fundamental physics requirements for stellar status.

What distinguishes a 'failed star' like a brown dwarf from Jupiter, according to the text's distinction between object types?
physicsastronomysciencedwarfstar