You can access all database options with a license, but usually you pick one for your project/analysis. Never mix different system models. The ecoinvent databases are named by:
version - "3.9.1" as an example
system-model - "Cutoff": system model "Allocation, cutoff by classification"
system-model - "Consequential": system model "Substitution, consequential long-term"
system-model - "APOS": Allocation at the point of substitution
datasets - "UNIT": database with unit processes UPR (recommended)
datasets - "LCI": database with only system processes (fully aggregated life cycle inventories LCI) instead of unit processes
other - "Regionalized": additionally to the "standard" ecoinvent database with unit processes, it is also possible to download the same databases with additional informations on the location (region-specific) of some elementary flows in the processes, where applicable (see the database implementation report for more information)