Both the schema are system defined schemas. _SYS_BI schema is used to store all the metadata of created column Views.
It is different from _SYS_BIC and _SYS_REPO schema and you can understand this from below −
SYS_BI − This schema stores all the metadata of created column Views.
_SYS_BIC − Whenever you activate any HANA Modeling view, it is stored under _SYS_BIC System defined schema.
_SYS_REPO − Whatever the objects are there in the system is available in repository. This is used to create required run time objects.