Gorillan skulle inte ha en chans, det är bara att titta på viktskillnaden:
"The heaviest gorilla recorded was a 1.83 m (6 ft 0 in) silverback shot in Ambam, Cameroon, which weighed 267 kg (589 lb)."
https://en.wikipedia.org/wiki/Gorilla
"One study found that the average weight for an inland male grizzly was around 272 kilograms (600 pounds), and the average weight for a coastal male was around 408 kg (899 lb).
On the other hand, an occasional huge male grizzly has been recorded which greatly exceeds ordinary size, with weights reported up to 680 kg (1,500 lb)"
https://en.wikipedia.org/wiki/Grizzly_bear
Sedan har björnar stora klor, större tänder, tjock päls och betydligt tjockare skyddande fettlager.