This is when the buyer only owns the structure on the land and has to pay rent to the person who owns the land...Good example is mobile home park where the land is owned by a different person than the than the person who owns the mobile home.
Lot rent, is just that, you are renting/leasing the dirt and you own the house or mobile home, often refer to as personal property. Often these lot leases can be lock in yearly or for longer period of times such as 99 years. So if you elected to sale down the road the lot / lease would convey along with the purchase. Keep in mind you receive no tax ratification / deductions for leasing the land.
Hope that is helpful. Please feel free to contact me with any additional questions you may.
Legends Real Estate