I always think of "bootlegs" as unofficial releases, and "pirates" as unlicensed reproductions of official releases. An analogy in the music world (where the term is more common), if I bought "Frampton Comes Alive" in Best Buy, that would be an official release. If I bought it from some street vendor in Malaysia for a buck, or downloaded it for free off of Gnutella, that would be a pirate. But if I bought "Frampton Comes Alive at the Local VFW" it would be a bootleg. At least, I don't think there are any official sources of Frampton playing at the local VFW. Of course, I could be wrong.