Minced beef technical questions

[QuietContraryMary]

So 5% fat:

groceries.asda.com/product/beef-mince/asda-butchers-selection-lean-beef-mince-typically-less-than-5-fat/910002713230

4.3 grams fat, 27g protein, 0.26g salt

No carbs or fibre = 31.6 grams

groceries.asda.com/product/beef-mince/asda-butchers-selection-beef-mince-typically-less-than-20-fat/1965516

20% fat:

16g fat
23g protein
0.37g salt

no fibre, carbs
total = 39.4g

So despite being more expensive, the 5% stuff doesn't seem to have significantly more protein, only 4g, while the lost fat is 11.7g.

So they just replace the fat with water? Or is it more a case of lean meat being much higher in water than the fatty parts are?

And do they use the same cut of meat, just trimming off the fat? Or is it a different cut?