Its just thicker. The queen is supposedly heavier being silicone based organism comprised entirely of chitinous armor and thick acid blood
So here is some stats for the first queen from Aliens and the Irex
xenomorph_queen_1986_01.jpg Xenomorph Queen '86
AKA: Alien Queen; Species: Internecivus raptus; Type: Alien
Height: 20 ft; Weight: 10 tons
Attributes: Bites, claws, tail, exoskeleton, ovipositor, acid blood
Powers: None revealed
Intelligence: Low (hive mind)
Land Speed: Moderate
. rex
HYBRID OF
Giganotosaurus[1][2][3] + Majungasaurus[1][3] + Carnotaurus[1][2] + Rugops[1] + Therizinosaurus[2] + Tyrannosaurus rex + Pycnonemosaurus + Quilmesaurus + Viavenator + Velociraptor + Deinosuchus[4] + Cuttlefish + Tree frog[5] + Pit viper[2] + Unspecified number of modern animals[3]
DIET
Carnivore
HEIGHT
6 meters (20 ft)[5]
LENGTH
15.2 meters (50 ft)[6][5]
WEIGHT
8 tons (16,000 pounds) [According to "Jurassic World Survival Guide"]
RANGE
Isla Nublar
BIRTH TYPE
Egg
According to their wikis (best I could find in single search) she is actually 2 tons heavier and is capable of tearing through steel, her inner bite can punch through dlex Yautja armor which far surpasses any Earthly material. And it will one shot pretty much anything if she gets a head or chest shit. Also her tail can punch through the IRex while it's charging head first.
They aren't displayed in the movies remotely close to how they are in the novels and comics but nothing is, I doubt she has the raw stout power of the IRex but she is quite powerful. Her body seems like it's made to fight enemies a bit smaller than her though as opposed to the IRex thick neck and huge Jaw that can kill her ifnhe gets her head. Which would still kill him. Like Imp said it's a dirty little kamikaze trick that allows her to kill things out of her weight class