What are hybrid stores and there advantages and disadvantanges?

Each Vendor (Netapp, HPE, EMC, Hitachi...) has its own definition but basically Hybrid means "mixing Flash storage (SSD) and HDD disks". I think the main reason for this is pricing. So the main advantage is to have the possibility to store high availibility Data in SSD tier (expensive) and the less needed data in classical and cheaper tier (HDD, SAS, SATA, NL SAS...)