It's of importance to note that historically, "stone", "gravel", and many other related terms have great regional variability. It is always advised to make certain what is meant by such terms when they are being used.
Although the term "gravel" does have a specific engineering definition (aggregate of a certain size range), in design specifications the terms "crushed stone" and "crushed gravel" have come to have a slightly different and generally agreed upon meaning. Using these terms together is a way of specifying several things at once, including the source of the material, and its size, as well as its shape characteristics.
In this context, "stone" is rock that is sourced- usually quarried- from some parent rock (such as granite, limestone, and dolomite). Stone has generally not been naturally created by weathering. On the other hand, "gravel" is rock fragments sourced from an existing deposit of weathered rock, often from rivers and streams, but also gravel pits. As such, gravel tends to be more rounded in shape.
The modifier crushed specifies two things at once. First, that the aggregate be angular in shape and not rounded. Second, that the aggregate consist of a variety of sizes. When required, these very general terms are often fleshed out a bit in the design specification by requiring the aggregate meet some kind of gradation curve, or a durability test (such as the LA Abrasion Test).
When these terms are listed such as in a design specification like the one quoted above, the specification is allowing for just about any material source, so long as the material meets the size and shape requirements.
If the material is high quality and meets specification, telling the difference between the two on site should be difficult. Look for smaller rounded pieces in the stockpile that were missed by the crusher to identify a gravel source. Rounded pieces from a quarried stone should be very rare.
