Comparing top 10 college lists by country

How should we compare a list of alleged top 10 universities from country Y, with another similar list for country X? If we assume that these universities will draw proportionately from the top of the student pool in their respective countries of origin, then one way to compare the two lists would be to compare enrollment in these universities as a % of the student pools in the respective countries.

What happens when we use this method to compare the so-called top 10 universities in the UK as determined by The Complete University Guide, with a similar so-called top 10 list of universities in the US as determined by US News?

It appears that the UK top 10 enroll 118,880 students in total (6.5% of UK undergraduates). On the other hand the US top 10 only enroll 58,142 students (0.6% of Undergraduates in 4 Year institutions). In other words the UK top 10 enroll 2x as many students as the US top 10 in absolute numbers. On the other hand, in terms of the proportion of undergraduates in the respective countries enrolled in top 10 universities, the UK top 10 undergraduate enrollment is 11x that of the US.

Based on US News rankings, one would have to aggregate the undergraduate enrollment at the top 50 universities in the US to reach 6.3% of the student pool – a sliver below the 6.5% of undergraduates in the UK that are enrolled in the top 10 UK universities.

What about US liberal arts colleges? One would have to aggregate the top 56 to get to 118,638 students enrolled (1.1% of total undergraduate enrollment in 4 Year institutions) – a figure comparable in absolute terms to the 118,880 enrolled in the top 10 UK universities.

In short, top 10 lists are not comparable across countries.