Closing Recommendation
Both are heavy Liebherr mining excavators, so the choice is diesel that works anywhere or electric with a bigger bucket. Choose the Liebherr R 9200 G7 when your mine is remote or has no steady power, when you want faster travel and a big fuel tank, and when easier moving matters. Choose the Liebherr R 9250 G6 when your site is fixed with a strong power supply, and you want a bigger bucket, clean power and lower running cost. Also check which brand service point is near your mine. So match the machine to your work: R 9200 G7 for any site with no steady power, R 9250 G6 for a fixed, powered mine with the biggest bucket and low running cost.