The categories that Google uses in Maps have always been confusing. They have their own very limited list and then they integrate categories from their other providers in a non-transparent way that causes confusion.
In a first step to making this more tranparent, Reuben Yau has created the first full summary of Google’s own Local Business Center categories.
Previously Reuben wrote: The other thing I noticed is that the category for that site is Gazebo Builder which is taken from Acxiom’s database, but that category is not present within GLBC. FYI Acxiom is the database behind yellowpages etc.
It would be of interest to gain a complete list of these categories and attempt to map them to Google’s.