The O-1 standard sits at 8 C.F.R. § 214.2(o)(3). For O-1A, the petitioner has to demonstrate extraordinary ability in the sciences, education, business, or athletics through sustained national or international acclaim, evidenced by either receipt of a major internationally-recognized award or by satisfying at least three of the listed evidentiary criteria. For O-1B in the arts, the standard is "distinction," which is statutorily lower than extraordinary ability. The O-1 is for the duration of the activity for which the person is admitted, in increments of up to three years initially with one-year extensions.
The EB-1A standard sits at 8 C.F.R. § 204.5(h)(3). The petitioner has to demonstrate extraordinary ability through receipt of a major internationally-recognized award or by satisfying at least three of the ten enumerated criteria, followed by the Kazarian v. USCIS, 596 F.3d 1115 (9th Cir. 2010), final-merits analysis. EB-1A is a permanent-residence classification.
The two standards share regulatory text and evidentiary structure but are read differently in current practice. O-1 adjudications, while not lenient, have generally credited records that EB-1A adjudications scrutinize more aggressively. The specific divergences include: the final-merits analysis is unique to EB-1A; the EB-1A standard requires sustained acclaim in a way that O-1 adjudications sometimes treat more flexibly; and the EB-1A officer's discretion at Step 2 of Kazarian introduces a layer of analysis that the O-1 does not have. The O-1 also has an employer or agent; EB-1A is a self-petition, which removes the employer-side filings but places the full evidentiary burden on the individual.
The premium-processing regulation at 8 C.F.R. § 103.7(e) applies to both O-1 and EB-1A.