#####tl;dr [&& and   have higher precendence](http://phrogz.net/ProgrammingRuby/language.html#table%5F18.4 )

Difference between ‘and’ and ‘&&’

cat = 'meow'
dog = false


answer = cat && dog
=> false

answer
=>  false

answer = cat and dog
=> false

answer
=> 'meow'
Similarly with ‘or’ and ‘  
cat = false
dog = 'bark'

answer = cat || dog
 => 'bark'

answer
=>  'bark'

answer = cat or dog
=> 'bark'

answer
=> false

I generally follow this style guide