I'm confused. What's the difference?
Let's say a country has only a single 20% tax band that kicks in at 20k.
If you earn 40k, your marginal tax is 20%, but only 20k of your earning is above 20k, so you pay 20% * 30k = 4k in tax for an effective rate of 10% (4k of 40k).
Most countries will multiple tax bands plus deductions which complicates this, and most places very few people have enough of their income taxed at their marginal rate for their effective rate to approach their marginal rate.
So if you have a marginal rate of 50% but it only kicks in when you earn over a certain amount, you will be paying less than 50% overall (your effective rate).
If you made $100k, paid $25K in income taxes, and were in a 33% bracket, your effective rate was 25% and your marginal rate was 33%.
They quoted marginal rates, not effective rates, which is usually the case when people start talking about these high numbers.