Русско-англо-русский юридический словарь

A servitude cannot impose the performance of a positive duty on the owner of the burdened property but only duties either to refrain from exercising certain rights to which an owner could be otherwise entitled (negative servitude) or to suffer certain things to be done to his property which an owner otherwise could be entitled to forbid or resist (positive servitude). (Wikipedia)

An affirmative easement is the right to use another's property for a specific purpose, while a negative easement is the right to prevent another from performing an otherwise lawful activity on their property. (Wikipedia)