No source here ranks a giraffe or a lion as stronger than the other. Animal Diversity Web says adult giraffes can defend themselves well: they stay vigilant and are capable of running quickly and of landing deadly blows with their front hooves. The IUCN/SSC Cat Specialist Group describes the lion as very muscular, with shoulders and forepaws that are particularly massive and powerful.
Animal Diversity Web names lions as the main predators of giraffes, and says leopards and hyenas have also been known to prey on them. It adds that young, sick or old giraffes are what most of their predators target. The San Diego Zoo Wildlife Alliance gives a different list for giraffes: besides humans, only lions and crocodiles hunt them.
Giraffe kicks and horns

The San Diego Zoo Wildlife Alliance describes a karate-style kick that giraffes use, if they have to, to defend themselves, and calls it deadly. Giraffe horns are called ossicones, and Animal Diversity Web describes them as bone protuberances covered with skin and fur.
The lion’s build and how it hunts

The IUCN/SSC Cat Specialist Group says the lion’s body is built for strength and for short bursts of high speed. It says the massive, powerful shoulders and forepaws let lions tackle and subdue large prey. The same group says male lions hunting on their own are efficient hunters that typically take on large prey such as buffalo and giraffe. According to the San Diego Zoo Wildlife Alliance, a lioness will often suffocate prey by clamping her jaws on its nose and mouth.
Weights and sizes
According to Animal Diversity Web, giraffe bulls weigh up to 1,930 kg and cows up to 1,180 kg. It lists a male giraffe at 5.7 m from the ground to the horns, with 3.3 m at the shoulders and a long neck of 2.4 m.
For lions, Animal Diversity Web says adult males typically weigh 189 kg and females weigh 126 kg on average, and the heaviest male recorded weighed 272 kg (Mount Kenya). It gives 1.2 m as the average male height and 1.1 m as the average female height.
Sources
- Animal Diversity Web: Giraffa camelopardalis (giraffe) | INFORMATION
- Animal Diversity Web: Panthera leo (lion) | INFORMATION
- San Diego Zoo Wildlife Alliance: Giraffe | San Diego Zoo Animals & Plants
- San Diego Zoo Wildlife Alliance: Lion | San Diego Zoo Animals & Plants
- IUCN/SSC Cat Specialist Group: Living Species – Lion | IUCN CatSG
- Proceedings of the Royal Society B (via PubMed Central): Bite club: comparative bite force in big biting mammals