SharePoint Group Security Principals

// SharePoint Groups that are Security Principals on this website
SPGroupCollection groups = web.Groups;
Response.Write("All SharePoint groups in this site: "+"
");
foreach (SPGroup group in groups)
{
Response.Write(group.Name + "
");
}

// All SharePoint Groups in this site collection
groups = web.SiteGroups;
Response.Write("All SharePoint groups in this site collection: " + "
"); foreach (SPGroup group in groups)
{
Response.Write(group.Name + "
");
}