Yes and No, some people do combine them but a Refugium can also be a separate tank with cheato and other "plants" growing in it. Basically it is a refuge place for pods and other gogga's to grow and then flow into your tank to feed fish and corals.
The refugium is something,some think of as a water cleaner these days,as an algae scrubber does.
The way most people make there refugiums is far from this.
For the algaes to clean your water of phosphates,toxins,etc,they have to be growing fast and thick to convert as the phytoplankton does to clean the ocean,of which we attempt to mimick,sometimes not so good.
Keep it shallow,have a large overal area,strong over all current,broad spectrum t8s or t5s,trim it weekly and you have a winner.
Pump to it from your sump to over flow back.it will work better if you have the room.