A bigot is one who holds offensive opinions based on little or no evidence, other than inherited thought. Ridicule is to decry someone's ideas as being laughable, but this may, or may not, be done on a sound basis. An opinionated observation is based on a strongly held viewpoint which again, may nor may not stand up to scrutiny.
Examples -
"All foreigners are scum."
"The idea that all foreigners are scum is so ludicrous, I can't be bothered to respond to it."
"I think that all foreigners are scum, always have, always will, and nothing you can say will change my mind."
For the benefit of newcomers to the Site, these are examples, and do not in any way reflect my personal views.