Breadth and Scope

I believe your answer is in the next sentence. I think that the author is trying to explain "breadth" as a range or spanning across several areas and "scope" as different levels or in comparison to some kind of depth.

I tend to agree with Oristar on this one. Non-native English speaker as he is, it is difficult to differentiate in meaning between these two.

This is a nasty habit in English; we use similar words or alternatives in pairs, to indicate a singular concept.

Examples:
aims and objectives
goods and chattels
flotsam and jetsam
far and away
hearth and home
can't think of any more right now, but there are hundreds

Thanks McTag, that is so clear now.
Also thank MichaelAllen.

Just here to quibble -- flotsam and jetsam are two different things. Flotsam is manmade stuff floating on the sea or washed up on the shore (as after a storm); jetsam is manmade stuff that was thrown off a ship deliberately (as to lighten the load) and is floating on the sea or washed up on the shore... Now if that's not immediately obvious and a difference that clearly needs to be made, I don't know what is...

Kith and kin, that's another.

Now Wy, be it known to the court that I was aware of the distinction in legal terms between flotsam and jetsam, but I would respectfully contend that in the context of daily use they are normally thought of as one, and not in their strictly legal sense either.

(Thinks....are they in daily use? Probably not. )

root and branch
lock, stock and barrel

plural groups, signifying one entity

Any more?

Cease and desist, although I use it a lot, and explain the differentiation to my kid every time she seems to forget:
Cease = Stop that this instant!
Desist = Don't start up again in twenty seconds!

Useful for tapping, fidgiting, picking, whining, etc.