Here the 3 main differences between the O1 and the H1B visa:
Between the two visas H1-B has a very limited and rigid time-frame. In the event that you have requested the H1-B, you will have to leave the country once it is granted (sometime after April 1st, when the application is opened) until October 1, which becomes effective. With the O1-B you will have to leave the country only to obtain the new O1-B visa stamp in your passport.
The O1-B Visa, or “Artist Visa” is given to candidates that demonstrate extraordinary abilities by national and international acclaim. You must build the case with evidences that set you apart from the crowd with awards or professional experience in the leading companies in the US. With the H1-B options are very limited. UCIS only issues 65,000 H1-B visas per year (to all countries and all disciplines) and since 2013 they registered more than 100,000 applications the same day application opens!
Commitments from company
To receive the O1-B Visa you must get high commitment from the Company. The Company has to sponsor you covering all related expenses (visa, lawyers, health insurance,..), acquiring a 3 years commitment with the employee and having to pay you a high salary to justify his hire instead of hiring a local one. All these aspects makes American companies have a harder time to sponsoring internationals. The good thing is that all of our ex-participants of the Job + J1 Visa Program of Architect-US which have applied to the O1-B have achieved it!! Which means that by our criteria of excellence and work, this can be an option for the Host Companies that want the participant to continue with them once the J1 is completed.