The H-1B, L-1, and O-1 visas are all employment-based nonimmigrant visas, but they have different purposes and have special eligibility requirements. The H-1B visa is for professionals in specialty occupations, which require a minimum of a bachelor’s degree or equivalent in a specialized field, such as engineering or finance. It still requires employer sponsorship, it has a strict annual cap, and it typically allows for an initial stay of up to three years, extendable up to six years. 

For multinational firms, the L-1 visa enables moving workers from an overseas office to a U.S. location. The L-1A category is for certain managers and executives, while L-1B is for certain employees with specialized knowledge. It does not have any annual cap, as L-1A holders are able to stay for up to seven years, while L-1B holders are able to stay for up to five years. The O-1 visa is intended for certain people displaying extraordinary capability in fields such as science, arts, education, business, and even athletics. It requires showing sustained national or international acclaim. 

As it can be extended in one-year increments as long as the individual continues working in their field, it does not have a maximum stay limit. Not unlike both of the H-1B and also the L-1, the O-1 visa is plainly not tied to such a specific employer, and thereby allows far greater flexibility for either self-employment or even multiple employers.