H-1B . Nonimmigrant Visa
The H-1B visa is a non-immigrant visa that allows individuals from all over the world work in the United States for a sponsoring employer. This visa type was designed specifically for workers in specialty occupations that require a higher level of education or technical experience such as science, medicine, engineering and mathematics.
For international students in the United States wishing to stay longer than their OPT period, an H-1B visa can be a great way to stay employed in the country and continue gaining experience in a given field. Generally this visa is granted for a period of three years and can be extended for an additional three years for special circumstances. Unlike other visa types where you can apply for yourself, the H-1B visa requires your employer to apply on your behalf.
O-1 Nonimmigrant Visa
O-1 is a visa for individuals at the very top of their respective field in science, arts, education, business or athletes, who have sustained national or international acclaim. O1 Visas are employer specific visas. The validity depends on the duration of the position or event. The duration can range from short stopovers to a multi-year project/assignment.