Both sites seem to rely on Google's mapping API, but because partyGPS includes all location types (liquor stores, bars, clubs), a single map takes a while to load. BMP, on the other hand, is fairly quick. You might think that has to do with the fact that BMP only lists beer locations but, actually, the BMP listings for my zip code were almost as exhaustive as those on partyGPS.
BMP offers other features that add to the site's usefulness:
- Search function: Allows you to search by city or zip, and includes an additional search function for brewery by region. I'm not sure why they only do this for breweries, though; what if I'm interested in only searching for stores?
- Cell phones: BMP is viewable on your cell, so if you're out and about and desperately need a beer, you can find one. If I knew where I was going, however, and just needed an address, then I would probably just call information.