If you use Make Perspective Camera and set the FOV to 180 degrees, is that the same as fisheye?
No; the geometric projections are different — Vuo’s perspective camera uses a rectangular frustum, and Vuo’s fisheye camera uses a spherical sector. (A rectangular frustum can’t actually go quite all the way to 180° since it becomes degenerate.)
If you re interested in greater-than-180° rendering, see the feature request, Render scenes to equirectangular panoramas and cube maps.