Sam Adams etc. tipped a bunch of tea over board after the tea act had given the east India company trading rights that would have screwed many Boston merchants (and therefore their employees).
The L.A. riots broke out because of an incident of white police officers beating a black guy (who was acting like an asshole towards them) and a backdrop of racial aggrevation between blacks, hispanics and Koreans(the latter two groups having massively increased their population in traditionally black neighbourhoods of L.A.). The riots that broke out caused widespread arson and looting. Roughly 60 people died, about $1 billion of damage, Asian stores were major targets, black mobs attacked white drivers, people shot at emergency services and so on.
The Boston Tea Party was a very political act involving about 60 people which was generally peaceful whereas the L.A. riots were a venting of all sorts of crap involving massive amounts of random violence. The Boston Tea Party was not a wild out of control riot. The "rioters" swept the decks afterwards and had the ships' first mates declare that only the cargo of tea had been destroyed.
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