How much caffeine is in a 2 shot of espresso compared to coffee?

I'm curious to know, how much caffeine can one expect to consume in a two-shot espresso compared to a regular cup of coffee? It's a common misconception that espresso is more potent in terms of caffeine content, but is that really the case? I'd like to understand the difference in caffeine levels between these two popular coffee beverages and what factors might influence the outcome.