While no one can be unbiased, we're all influenced by our own preferences, including critics, critics will tend to be proper cinephiles. They'll judge movies passed on their artistic merit, performances, technical elements etc. A critic's judgement is based on how good the product is.

Audiences will judge it purely based on their enjoyment of it. It's why The Last Jedi scores differ so wildly. On a technical basis it is a good film, but the audience, which for the majority consists of fanboys (and girls), who don't like the direction the story took.