What is the difference between gravity anchorage and tunnel anchorages in suspension bridges?

Gravity anchorages consist of three main parts, namely the base block, anchorage block and weight block. The weight block sits on top of anchor block and its weight is not used for resisting the pull of cables. Instead, its vertical action presses the cables vertically downward so as to turn the pull of cables against the foundation.

Tunnel anchorages resist loads from cables by mobilization of shear friction between the embedded concrete anchorage and the surrounding foundation.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.