I ride in both cities. And cab drivers in both cities can be a major challenge. When I was a bike messenger in Boston in the 80's (just as bike messengers were gaining in popularity) bikes were seen as competition for package delivery money so there was a particular kind of hostility.
In general I would say NYC cabbies drive faster and are more aggressive. In Boston they sort of slowly crawl up your a** or drift across (with no signals) to drop off or pick up a passenger.
I have, on occasion, had cabbies in both cities be kind to me while on my bike. I was so thrown by this I was barely able to respond.