While going through the topic called "Combinations of Ducted Jet Engines and Rocket Engines" in Chapter 1 of Sutton & Biblarz's Rocket Propulsion Elements, 9th Ed I found the section below.
Line 2 tells that air-augmented rocket propulsion combines the principles while line 1 of 2nd paragraph tells that integral rocket-ramjet propulsion combines the actions of rocket and ramjet!
Is the architecture of the above types of propulsion techniques same?
FIGURE 1–7. Simplified diagram of an air-launched missile with integral rocket–ramjet propulsion. After the solid propellant has been consumed in boosting the vehicle to flight speed, the rocket combustion chamber becomes the ramjet combustion chamber with air burning the ramjet liquid fuel. Igniter and steering mechanisms are not shown.
Ducted rocket propulsion systems, sometimes called air-augmented rocket propulsion systems, combine the principles of rocket and ramjet engines; they give higher performance (specific impulse) than chemical rocket engines but can only operate within the earth’s atmosphere. Usually, the term air-augmented rocket denotes mix- ing of air with the rocket exhaust (made fuel rich for afterburning) in proportions that enable the propulsion device to retain those characteristics that typify rocket engines, for example, high static thrust and high thrust-to-weight ratio. In contrast, the ducted rocket is often like a ramjet in that it must be boosted to operating speed and uses the rocket components more as a fuel-rich gas generator (liquid or solid).
The action of rocket propulsion systems and ramjets can be combined. An example of these two are propulsion systems operating in sequence and then in tandem and yet utilizing a common combustion chamber volume, as shown in Fig. 1–7. Such a low-volume configuration, known as an integral rocket–ramjet, has been attractive
