One isn’t better than the other. They’re just different, and cater to different kinds of players. Here’s an infographic comparing some of the qualities between PUBG Mobile and Garena Free Fire. It also includes Rules of Survival, which you can ignore.
Some additional details:
PUBG takes a more realistic take on the battle royale genre. You deploy from a cargo plane, land down to the map, grab very familiar guns, and shoot anything that moves.
Bullets fired from guns use projectile simulation — which means it takes some time before your shots hit the target (based on the bullet velocities of the weapons you carry) and bullets will drop as they travel over time. If you are sniping from long range, you will need to fiddle with the scope and the travel distance of the bullet. This actually provides a more authentic feel per weapon.
· Realistic gunplay
· Authentic shooting
· Victory motto: “WINNER WINNER CHICKEN DINNER!”
Free Fire has more simplified gameplay with aim assist. It uses a hitscan/raycast system; bullets hit as soon as you pull the trigger. This makes Free Fire more casual than PUBG Mobile
The biggest difference here is the inclusion of classes. It has a bit of a similarity to Apex Legends where players can choose from a roster of characters, each with their buffs and power-ups that they can use to their advantage in the game.
· Casual shooting
· Has aim assist
· Includes heroes with unique skills
· Victory motto: “BOOYAH! SHOWTIME.”