A multi-tenant net lease (MTNL) is when you have more than one tenant, typically in a retail center, (although you could also have multiple tenants that are NNN in a medical building or an industrial building). The most common is a retail building.
Unlike single tenant where all the income relies on one tenant, in multi -tenant the income is generated from multiple business owners. That can be a positive or a negative based on the tenant credit quality and structure of the leases. Not all retail centers are NNN leases. Some are more gross leases or a mix of NNN and gross leases. The less straight forward a retail center is with the leases being the same, the more you have to really dig in and analyze the property heavily to see if it is still a viable investment option.
Multi-tenant centers can be more work than single tenant properties but usually still much less work than residential or multifamily type properties. Those properties have to deal with residential/landlord tenant laws, which, depending on the state, can be heavily biased in favor of the tenant.
The level of work with an MTNL center will depend on the number of tenants and whether they are national, regional, franchisee or mom/pop in nature.
Typically the smaller the tenant, the higher the workload and an increase in potential risk.
Residential properties can also be harder to scale (especially the smaller ones) whereas MTNL commercial can be duplicated over and over again with the right systems in place.