* Pretensions is a noun and refers to a claim or assumption of importance or superiority, often unjustified. It describes the attitude or behavior of someone who pretends to be more important or knowledgeable than they actually are.
* Example: "He had lofty pretensions about his artistic abilities, but his paintings were amateurish."
* Pretentious is an adjective describing someone or something that is intended to impress by affecting greater importance, talent, culture, etc., than is actually possessed. It focuses on the quality or character of being overly showy or affected.
* Example: "Her pretentious pronouncements on art were easily dismissed by anyone with actual knowledge."
Essentially, pretensions are the act of being pretentious, while pretentious is the quality of that act.