Concretely they are the same, for an interpreted language. I think the distinction they are trying to make is between slowness due to general constraints on in

Concretely they are the same, for an interpreted language. I think the distinction they are trying to make is between slowness due to general constraints on interpreted languages vs. slowness because of particular features or implementation details of CPython's runtime. It is kind of like, bicycles are slower than motorcycles, in general. Let' say I have a Snake 3000 bicycle with a max speed of 4mph. And people say, it's slow because it's a bicycle, if you want a fast vehicle get a motorcycle. And the author comes along and say, well, yeah, bicycles are not that fast, but the Snake 3000 has an alternator that uses 80% of the bike's mechanical energy to run a seat warmer, if you removed that you could reach 20mph. So is the real reason for the Snake 3000's slowness "because it is a bicycle" or "because it has a pedal-powered seat warmer"? (The answer is both of course, but with respect to Python people rarely acknowledge the second one.)