Subletting means that a tenant sublets the entire apartment or a part of it. This normally requires a permit from the landlord.
By subletting the entire home the rental period is limited to a maximum of two years. The tenant's absence must be temporary and justified by business, study, travel or similar.
A partial subletting has no restrictions on the rental period unless otherwise agreed. Please note the number of residents may not exceed the number of rooms in the home. So no more than two people in a two room apartment.
By sublease the lease contract is not made by the landlord but by the tenant. This means that it is the tenant who is responsible for the actual lease agreement with the landlord during the sublease.