For me both topics are pretty much disjunct:
"BW on HANA Administration" would include (at least in my own understanding) topics like converting BW fact tables or DSOs to the SAP HANA optimized layout or optimizing the BW table distribution across scale-out nodes.
"SAP HANA Administration" is the technical administration of the SAP HANA database (e.g. backups, consistency checks, performance monitoring) which doesn't depend much on the actual application running on top.