Trademark - eg. 'Apple' computers and 'Apple' records;  'Astra'
  Margarine and 'Astra' cars.  There are 42 trademark classes.  In
  theory, 42 separate entities could legally be using the same
  trademark.

Trivia time.

Apple records (applecorp,  you have to say it to get the joke) Sued
Apple computers when Mac started doing audio/music stuff. They had
an agreement the apple logo and branding wouldn't be used for music
related business...

Way to go beatles!

-George