It depends on which areas of each genre you're talking about. I don't know a lot about goth, but punk can vary from bands like Sex Pistols, The Clash, The Ramones and Rancid to bands like Green Day and Blink 182. It's much the same for emo - it varies from some of my favourite bands (Sunny Day Real Estate, The Get Up Kids, Bright Eyes, even Death Cab) to some of the worst music you'll ever hear (Hawthorne Heights, Panic! At The Disco, Fall Out Boy). It's not difficult to make comparisons if you interpret it broadly - whilst Blink 182 are considered by some to be punk (pop-punk at the least), they are easily compared to emo bands like Fall Out Boy. On the other hand it's difficult to compare Bright Eyes to The Ramones.