First, Olympic weightlifting is extremely technical, and the development of strength for Olympic weightlifting is, to an enormous degree, a function of technical mastery. For the layperson and spectator, there may appear to be little difference between the performances of an amateur and a world-class professional, but imperceptible (to the non-expert) changes to the position of the body, to the position of the bar relative to the body, and to the timing of accelerations make an enormous difference to the lift—to such a degree that it can be the distinction between a world record performance and an accident! In Olympic weightlifting, technique is everything.
Secondly, the expression of strength (or more correctly power) in Olympic weightlifting is, after the development of a foundation of hypertrophy, primarily a function of neural (nervous system) development—not only in the form of skill learning, as described above, but more generally in terms of motor unit recruitment and the rate of force production that can consequently be expressed. That is, competitors train for hypertrophy in order to reach a physical size which is most representative of their genetic potential, but then continue to train to maximise their power at that size, thereafter.
I hope that helps.