What is the difference between a severe disability and a severe one?

The regulations guiding the step-two determination of whether a disability is severe is merely a threshold determination of whether the claimant is able to perform his past work. Thus, a finding that a claimant is severe at step two only raises a prima facie case of a disability. See Tackett v. Apfel, 180 F.3d 1094, 1100 (9th Cir. 1999). In contrast, the step-five determination is necessary to ascertain whether there is a significant number of jobs in the national economy that the claimant can perform. The grids provide broad categories of exertional limitations (and to a certain extent non-exertional limitations) and the range of jobs in each category. Thus, built into the step-five determination and the grids is recognition that the claimant has met the threshold requirement for a severe disability at step two.