Gross lease
Also known as a "full-service lease," a gross lease simply charges the tenant base rent. With this type of lease, the landlord agrees to cover nearly every operating expense necessary to run the building, including maintenance fees, property taxes, and building insurance.
Modified gross lease
A modified gross lease is a middle ground between net leases and gross leases. Here, the tenant usually agrees to pay a base rental rate, utilities, and a portion of their NNN costs. The details of what is paid by each party will vary according to the individual lease, but typically the tenant's NNN charge is based on the percentage of the building that they occupy.
N lease
An "N lease" is also known as a "single net lease." With a single net lease, the lessee is responsible for paying their base rent and the real estate taxes. Here, the landlord is responsible for paying the property insurance as well as any operating expense for the entirety of the lease term.