The discussion clarifies that an R2S turbocharger, a 2-stage turbocharger, and a twin turbo do not mean the same thing. A 2-stage turbo typically involves two turbos operating in series, with a low-pressure (LP) and high-pressure (HP) stage. Twin turbos can refer to either two separate single-stage turbos working in parallel or two stages in series. The example of BMW diesels illustrates the use of a small turbo for low RPMs and a larger one for higher RPMs, highlighting the versatility of twin single-stage setups. The R2S is described as a "compound turbo" that integrates two turbos into a single unit, differing from traditional setups.