Lines of Resolution
Lines of Resolution is a measure of how much horizontal detail can be reproduced on an analog display, most commonly a PAL or NTSC TV. Although technically it refers to the number of TV Lines per Picture Height, in common usage it may instead refer to the total number of TV Lines, which is 1.33 times as many lines. In order to avoid confusion it's best to use one of the other terms to indicate whether you're referring to lines across the full width of the TV or just an area with the same height and width (a 1:1 Aspect Ratio).
Although Lines of Resolution are often compared to digital resolution, in reality the two are completely different. The number of Lines of Resolution on a given TV will tend to vary from one source to another. Likewise, the number of Lines of Resolution from the same source, but on different TVs may vary as well. Digital resolution, on the other hand, measures only what's being stored or displayed, meaning a digital display has a set resolution regardless of the source, and each source has a set resolution, regardless of how (or whether) the same level of detail is represented by a TV.