price level vs price index

price level and price index both are nouns.

Word	Noun	Adjective	Verb	Adverb
price level	Yes	No	No	No
price index	Yes	No	No	No

As nouns, price level and price index are synonyms defined as:

price level and price index: an index that traces the relative changes in the price of an individual good (or a market basket of goods) over time

price level (noun)	price index (noun)
an index that traces the relative changes in the price of an individual good (or a market basket of goods) over time	an index that traces the relative changes in the price of an individual good (or a market basket of goods) over time