although Qwar1k says there is no difference, technically there is. I won't tell nobody (like the rest said, is grammatically incorrect) it means "I will tell everybody" but people who are ignorant use it, its a bad habit in America, there are a lot of people who say double negatives while talking "i ain't got none" "I didn't do nothing" If some one says "I won't tell nobody" they mean they won't tell anyone but its not how they should say it. I won't tell anybody is correct

Please always begin your sentences with capital letters. I won't tell nobody - this is wrong. But, you can say, I will tell nobody or no one. I won't tell anybody - this is right. You can also say "I won't tell anyone." Same as Jura.

i won't tell nobody - double negative construction, grammatically incorrect, used by some black guys a lot, in rap music, not only though .. i won't tell anybody - correct way to say this. no difference in meaning

You can also say, 'I won't tell anyone'.