In my opinion the area where the USN and RN approaches to SSNs differ is that of the fleet size. Ie USN has a large (many times more than RN) inventory of the SSNs. USN also projects its power all around the world.


Which is why, in my opinion, USN went for a relatively cheap, easy to produce general purpose platform set up (ie LAs and Virginias) while RN went for a more min/max ASW platform set up (T-class and A-class).


The set up is thus dependent on the Navy and the Country of origin, hence making direct comparisons difficult.
For example the late Soviet concept of Yasen class, the class intended to replace Oscars and Akulas (and be produced instead of 3, 3 Mark! classes of submarines designed in the 4th gen) had to have a lot of weapons to cover for all of it's intended roles - now Yasen has more than twice the weapons that Virginia class carries.
French on the other hand were looking at minimal SSNs and that is what they are building - small, cheap, good enough to conduct their mission set SSN platform.

Was doing some searching on the forums for something else and this thread came up.

The Astute v Virginia question was answered in 2012.

The winner being HMS Astute.

During the exercises HMS Astute Commanded by Cdr Iain Breckenridge (formerly CO of HMS Tireless & XO on HMS Superb) had many American dignitaries onboard.



https://www.gov.uk/government/news/hms-astute-arrives-home-from-us-sea-trials--2#:~:text=She%20'battled'%20against%20USS%20New,16 %2C400%20miles%20(26%2C400km).