Employment based and immigrant are not opposite categories of visa - these are orthogonal axes.

There are employment-based nonimmigrant visas like H1B and L1. Being a nonimmigrant visa means it doesn’t grant you a right to immigrate but some (including H1B and L1) are ‘dual intent’ visas meaning you can apply for an immigrant visa while in the US as a nonimmigrant.

There are employment-based immigrant visas, which have categories like EB1, EB2. Like all immigrant visas these are also known as ‘legal permanent residency’, LPR, or ‘green cards’.

There are also non-employment-based visas that are both nonimmigrant (eg visitor visas, student visas) and immigrant (eg family based green cards)