Ok since you like numbers here’s a real example comparing apples to apples: the 50 1.2 canon is over 20% heavier than Sony’s! Not to mention slower, clunkier and little noisy..
As a matter of fact Sony made huge advances in lens design, before Canon and Nikon were considered to be the best in this area, but now new Sony lenses are better in many respects.
Part of lens performance, let alone optical quality (which is not significantly different from Canon and Sony in practical experience), the most significant is all aspects of focusig - speed, precision ( especially in high speed burst mode), smoothnes, motor noise. And this all is achieved by using XD linear motors that have high torque and speed. This helps a lot in getting required performance, including what is required for video, and possibly to reduce size.
I wonder why Canon is still not using that in their new RF lenses? Just compare latest 50mm f1.2 from Sony and Canon. Huge difference in performace. Is this patent protected by Sony? Not sure as Fujifilm using the same in their latest GF lenses, providing high AF speed and accuracy which seemed before impossible for Medium Format lens systems ( e.g. GF 45-100 which focuses as fast so no one does feel any difference compared to FF systems). Also Fuji uses that in latest lenses for X system. May be they are cross patented as Fuji is a big customer for Sony sensors?
Would be interested to know why Canon still not using this approach and continue to use USM AF motors.
As for different design of Canon RF 70-200 and new Sony 70-200 (telescopic vs internal zoom) - both are good but I beleive they are aimed at slightly different groups of user. I think that Canon is more aimed at high end enthusiasts, event photographers, hikers, travellers where packaging size is important ( and this represents a huge user base), whereas Sony target audience is pro hybrid shooters where actual lens performance and conviniece for use both for photo and video is primary priority and portability is second or third one in the list of priorities. Also this is probaly showcase for latest Sony lens technology achievements - should be best of the best. I like second (Sony) approach better, especially ability to have accurate AF during zooming, and fast full range zoom using one finger. But if I need something more compact for events or travel - then Canon design would be better. But for this upcoming Tamron 35-150mm f/2-2.8 might be even better and possibly ideal choice, interesting if Tamron do version of this for Canon RF system.
I still keep my Canon EF 70-200 f/2.8L m2 with 1DXm2 and this combo works perfectly well when I do not need big high res files fom Sony a7rIV, on which I mostly use 70-200 f/2.8 GM. I tested Canon 70-200 on a7r4 using Metabones adapter and optically they are practically the same, may by Sony bit better, especially at corners, but I have very good copy, had ability to select best one from several ones from different batches at dealer shop at the place where I stayed at that time.
And one more thing regarding DSLR and mirrorles - DSLR AF on PRO bodied is still better and faster when using single point AF in difficult light condition, mirrorles ( even sony A9 and A1) are sometimes still struggling with that, but this depends on lenses, on last generation high-resolution GM lenses this much better practically on par with 1DXm2. This is why I still sometimes prefer 1DXm2 to the latest MILS.
Excuse me for any typing errors, it is difficult to avoid them on mobile devices.