I work and teach at a university physics department. That doesn't necessarily confer any special insight, but I would broadly agree with what has been said here.
Most physics degrees are accredited by the Institute of Physics. To be accredited, this means the degree must include content covering their "core" curriculum. That doesn't cover everything, but it does mean that the curriculum in Y1 and Y2 is broadly similar at most universities.
As @CautiousLurker01 said earlier, differences show up in Y3 and especially Y4. Although there will be some content that is the same at all universities, there will also be modules that are tied to the research interests of the department. The same is true for final year projects, which form a significant component of the final year mark. For example, we don't offer any projects in medical physics or medical imaging, because we have no investment in that. But (say) Nottingham has a major investment in medical imaging, because they have a major research group in it (MRI was invented there in the 1970s). But conversely, we will offer projects in areas that Nottingham don't. If I was recommending a University to someone for physics, I would first look at the specialization in Y3 and Y4, and how it matches their interests.
For MSc vs integrated masters, the major advantage of the BSc+MSc route is that you get to move institution before the MSc, maybe to somewhere that specializes in exactly your area. Also, as has been said, the MSc is a longer programme, usually with a more in-depth project (although often taught modules are shared between MSc and MPhys). The major downside is that it is more expensive, because the MSc counts as a postgraduate degree. There will be a range of views, but for me, the advantages do not outweigh the cost. However, many people do not agree. About 10 years ago we mostly saw applications for the 4 year MPhys degree. Now we see more applications for the BSc programme. It is not the only motivation, but I know anecdotally from speaking to some of our students that they are attracted by the option to change after Y3.
Theoretical physics was also mentioned. To further muddy the waters, if there is a real interest in this, remember that at some universities the mathematics department will have research groups that look like theoretical physics. The canonical example is Cambridge, where DAMTP covers astrophysics, high energy physics, mathematical biology, relativity and gravitation, and more. However, it isn't the only example. Many successful theorists come via this route.