Population 1 stars are metal rich stars. See related question.
Population 1 stars are typically young and metal-poor, found in the halo of a galaxy and formed from pristine gas. Population 2 stars are older and metal-rich, located in the disk of a galaxy and formed from gas enriched by supernova explosions of earlier stars.
Population I stars
Population II stars are the oldest in the Milky Way. These stars formed from the remnants of earlier generations of stars, and they have lower metallicity compared to younger Population I stars.
Population I stars are young and luminous like the Sun. Population II stars consist of globular clusters that are generally much older.
Population II stars are lower in "metals" than population I stars. By metals, astronomers mean anything other than hydrogen and helium.
Population I stars have more metals (heavier elements), and are generally younger, than the Population II stars. It is postulated that there are still older Population III stars, that have even less metals and are even older, but none have been discovered yet.
Population I stars
The oldest stars are classified as population III stars [See related question]
The oldest stars are classified as population III stars [See related question]
The so-called "Population I" stars are found in the galactic suburbs, which is where we live. Population II stars are concentrated toward the galactic bulge.
The hottest stars. Generally, globular clusters contain mainly old stars, population II stars