B-1 & B-2 visas are actually quite different. B-2 is the standard tourist visa that most visitors get to sightsee visit family etc. B-1 is a business visa that allows you to conduct business activities; conferences, meetings, etc. B-1’s are alightly more hassle to apply for, usually require a letter from hosting company/org, etc. Neither allow you to “work” here. I think Dennis and most pro athletes are technically supposed to get B-1’s but as you say enforcement is pretty tough and many folks aren’t aware of these nuances and either inadvertently or intentionally violate the technical rules. The very first question everyone arriving into the USA is asked on the I-94 arrival/depart form and USCIS officers is “purpose of visit?”, if its anything other than tourist or visit family, better have something other than a B-2 stamp in your passport… As we all now know, these issues can get very tricky, my guess is there are quite a few pro pool players now reading up in this stuff very carefully.
These links lay it all out pretty clearly, for anyone interested.
Generally, a citizen of a foreign country who wishes to enter the United States must first obtain a visa, either a nonimmigrant visa for a temporary stay, or an immigrant visa for permanent residence. Visitor visas are nonimmigrant visas for persons who want to enter the United States...
travel.state.gov
Find out the various visa types for foreign athletes to come and perform in the US.
www.visapro.com
I better get out of here, I might be being pretentious again


. I really am just trying to contribute accurate info…