Spread Centres first places all openings, then spaces each panel (between openings) and individual opening cripple studs evenly at nearest under entered Max Centres.
If you don't need to join sheeting over exactly placed stud centres, or exactly align trusses with studs, Spread Centres spaces the studs evenly, resulting in smaller centres, less studs, and prevents multiple studs close together.

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Exact Centres places studs at exact centres, even if there are multiple studs together at opening edges.

With Exact Spacing some opening edge studs may overlap common studs. To maintain centres, if the overlapped studs are not completely covered, the common stud position is adjusted (moved left or right). If the opening edge studs cover all but a small portion of the common stud (the Tolerance) the common stud is removed. No need to add a stud if the existing opening edge stud is only off by a few mm (the Tolerance). With Colour Code checked, adjusted studs are Blue. Common (un-adjusted) studs are Red. Opening studs are Orange.

Draw top and bottom tips of all studs (through all openings) to see where studs have been moved or removed for openings.

Drag Tolerance slider to raise maximum allowable centres and watch the diagram change as studs are added of removed. Max centres are labeled in diagram.

With Exact Centres, the first stud centre (gap) is adjusted smaller by 1/2 stud thickness so sheeting aligns with start edge of first stud (start of wall)

With Exact Spacing, some opening edge studs may overlap common studs. To maintain centres, if the overlapped studs are not completely covered, the common stud position is adjusted (moved left or right)
Adjusted studs are Blue
Common (un-adjusted) studs are Red
Opening studs are Orange
See also: Tolerance to set stud removal limits.