Anchors are used to support retaining structures. These can be multi strand multi anchor systems as we used at Gosport, simple grouted rods as used at Seaview or more sophisticated systems, capable of spanning voids, as used at Ventnor.
Soil nails, whilst apparently similar to anchors, work differently and are mostly used to stabilise slopes. We have successfully used soil nails in excess of 30m long for this purpose.