How are primary cosmic rays different from secondary cosmic rays?

The distinction between primary and secondary cosmic rays is based on their origin and their interaction with Earth's environment:

• Primary cosmic rays are the high-energy particles that originate from space and arrive at the outer edge of Earth's atmosphere. Because they are intercepted by the atmosphere, they cannot be observed directly at the Earth's surface and must be studied using high-altitude balloons, rockets, or satellites.12
• Secondary cosmic rays are produced when primary cosmic rays collide with atomic nuclei in Earth's atmosphere. These collisions create fragments of the original nuclei, as well as various short-lived subatomic particles such as muons and [neutrons]. It is these secondary particles that are typically observed at sea level.1

In the case of very high-energy primaries, these collisions can produce extensive air showers consisting of billions of secondary particles that reach the ground over large areas.3