How close is Boston and New York?

I'm curious, how close are Boston and New York, really? I've heard they're practically neighbors, but I'm not sure if that's just a saying or if there's some truth to it. Are they within driving distance of each other? Or is it more of a long haul trip? I'm planning a trip and I'm trying to figure out the logistics of getting from one city to the other. Any insights you can provide would be greatly appreciated.