What is the difference between a Part IV and a Part V designation under the Ontario Heritage Act?

Part IV and Part V are two different sections of the Ontario Heritage Act, and they correspond to the two main types of designation covered elsewhere in this Act: Part IV governs the designation of individual properties, identifying the specific heritage attributes of one building or site that require approval before alteration. Part V governs the designation of Heritage Conservation Districts, which apply to a defined area, and it's the section that provides the process for adopting a district plan governing multiple properties collectively.

Because these are separate parts of the same Act with somewhat different processes, notice requirements, and effects, a property owner needs to know which one actually applies to their situation, since the practical consequences, such as whether a district-wide plan applies to their entire neighbourhood or only the specific attributes of their own building were identified individually, can differ meaningfully. A property can potentially be subject to both, if it's individually designated under Part IV while also sitting within a Part V district. Anyone dealing with a designated property, or considering buying one, should confirm specifically which part of the Act applies, rather than assuming "heritage designated" means the same thing in every case.