What is the difference between 2 and 6 units in a non-regulated rent scheme? are 2 unit dwellings?

meaning private residence with a rental, covered under federal law? I don't think so. But if a building has more than three units, but less than 6 units, what category of tenant protection is available? I was on google scholar and using in various combinations, the search terms "more than three units" and "less than 6 units," the case law was unclear. Everything seem to dwell on 2 units. Suggest a new search string or let me know the category of law this falls within. Thanks to everyone reading this.