I dont know where you are quoting this from but its horse shit.
Tigers are bigger. Tigers are infinitely faster, most athletic and more explosive.Tigers are solo killers, a tiger depends on no one but himself. Tigers are meaner. If a lion has eaten reacently, you might be able to walk right past it with out dying. A tiger on the other hand, if you get in its area its going to fuck you up with out discussion.
and most importantly, technique. A lion has to have one front paw down at all times. it needs to have its base so that it can try to swipe powerfully with one paw. A tiger on the other hand can raise up on its hind legs and "box" the fuck out of a lion.
Check out the different clips in this. Multiple videos of a single tiger standing its ground against multiple lions and saying "what the fuck is up bro" and forcing them back. Before the lion can even get close to try and land a powerful strike the tiger has already hit it with a 5 piece and soda in the face.
tigers are confirmed to kill BEARS at times. nothing is fucking with a tiger in a fair fight that is remotely close to the same size.
at range/in the pocket the lion is bewildered by the speed and accuracy of the tigers paw swipes. in the clinch, even if the lion gets a dominant position on top of the tiger the tiger is able to just explode out of it with pure athleticism and reverse the position and slam the lion.