Problem with difference between IGetVertices and GetVertices

CComPtr vrtxFossa;

hr = pBody->IGetVertices(vrtxNumber,  &vrtxFossa);

hr = pBody->GetVertices(&Variant);

It seems that, GetVertices could get all the Vertices? IGetVertices could get only one vertex? If I am wrong, how to retrieve all the points and the coordinates on the body? Thanks.

SolidworksApi macros