Scale vs Ruler
Scale and Ruler are two words that are often confused as words that denote one and the same object. They are in fact not so. There is some difference between their connotations.
A ruler is sometimes called as a rule or simply as line gauge. It is an instrument used often in geometry and engineering drawing. It is important to know that a ruler is necessarily a straightedge to draw or rule lines. Since it rules lines it is called as a ruler. This is the reason why a ruler often contains calibrated lines that are employed in measuring distances.
A scale on the other hand is simple kind of ruler that is used in geometry to measure length. It is limited in use whereas a ruler is unlimited in use. It is interesting to note that there are several kinds of scales. Some of them are engineer’s scale, linear encoder, linear scale, vernier scale and architect’s scale. Linear scale is used in the showing the scale of a map or a chart. Engineer’s scale is used in measuring the lengths within rooms.
A scale is virtually used for measurements along a straight line. A ruler need not be used for this purpose. The use of scale is simple in purpose whereas that of a ruler is complex in purpose. A ruler with straight edge is used with a little bit of an extra advantage than a scale. A ruler is used very effectively in drawing accurate graphs in algebra and other math topics.
There are circular rulers too and their use is different from the straight edge ruler. A circular ruler assists you well in measuring the distance around the edge of a curve. You cannot use a straight edge for it though. These are the differences between a ruler and a scale.