These two phrases refer to the same group of people. Here the second phrase is used to describe the first phrase. AT: "the leaders, who are the heads of the clans of Israel" (See: [[rc://en/ta/man/translate/figs-parallelism]])
Here the word "you" is plural. Yahweh is speaking to Moses, but he his referring to the priests. The priests will blow the trumpets, Moses will not. AT: "When they blow a loud signal" (See: [[rc://en/ta/man/translate/figs-you]] and [[rc://en/ta/man/translate/figs-metonymy]])