Hybrid refers to the sim card tray and slot and dual sim refers to it according to sim cards which can be from two different networks.
"A Hybrid SIM Slot is one which can function both as a SIM card slot and a microSD card slot. This means you can either put another SIM in a hybrid SIM slot and use your phone as a dual SIM smartphone or you can put a microSD card in it for expanding the memory of your phone."
This is the model I own as per my signature below.
The Note 9 being sold by Samsung directly are as such and can either accept two network sim cards or one sim card and a sd card.
The Samsung Note 9 being sold by UK networks are usually single sim card and sd card models