You can analyse and use the olympics lifts in many many ways. One is to view the full skill is a pressure test for your front and overhead squat. The pure ” beautiful” form of the lifts are seen as the squat clean and squat snatch.
Put in other words, it tests if you own a superb front and back squat to the extend that you can jump into it with a great big weight. Any squat wobble or misunderstanding of your squat form means that, under pressure, you won’t be get under the bar.
Take home message: don’t skimp on your front squat and overhead squat practice!
It’s a big, big, sweep of the arm, but most of your lifts can be (could be) compared to your back squat. If you back squat 100kg, the chances are you can snatch up to 60kg, and clean 75kg. Bear in mind these figures could vary by as much as 15%
Christian Thibaudeau adds extra ratios and insights here
Waxman’s gym has a fascinating “Weightlifting Lift Calculator” here