The following information provides a summary of the categories of business travel allowable on B-1 visas and is not to be construed as legal advice.
Applicants who desire to enter the United States for business and who are otherwise eligible for visa issuance may be classifiable as nonimmigrant B-1 visitors if they meet the criteria described in 9 FAM 402.2-5(B) through (F). Admission with Electronic System for Travel Authorization (ESTA) approval allows for the same activities as contemplated for a B-1 visa holder admitted in that status.
Engaging in business using a B-1 visa entails business activities other than the performance of skilled or unskilled labor. Thus, the issuance of a B-1 visa is not appropriate for applicants who intend to obtain and engage in employment while in the United States.
If a business traveler seeks to engage in activity not clearly covered in this guidance, the traveler should apply for a more appropriate visa, such as a petition-based work visa, at their U.S. Embassy or Consulate.
NOTE: Incidental expenses or remuneration -- 9 FAM 402.2-5(F)(1): A nonimmigrant in B-1 status may not receive a salary from a U.S. source for services rendered in connection with their activities in the United States. A U.S. source, however, may provide the applicant with an expense allowance or reimbursement for expenses incidental to the temporary stay. Incidental expenses may not exceed the actual reasonable expenses the applicant will incur in traveling to and from the event, together with living expenses the applicant reasonably can be expected to incur for meals, lodging, laundry, and other basic services.
USCIS: B-1 Temporary Business Visitor
https://www.uscis.gov/working-in-the-united-states/temporary-visitors-for-business/b-1-temporary-business-visitor
Department of State: Visitor Visa
https://travel.state.gov/content/travel/en/us-visas/tourism-visit/visitor.html
9 FAM 402.2
https://fam.state.gov/fam/09fam/09fam040202.html