restrictive & non-restrictive clauses

  1. “We went to the house that collapsed yesterday.”
  2. “We went to the house which collapsed yesterday.”
  3. “We went to the house, that collapsed yesterday.”
  4. “We went to the house, which collapsed yesterday.”
    Please explain the differences between these sentences.

#1a and #1b are understood as defining relative clauses. Some people (including me, when I’m paying attention) prefer “that”, but others are indifferent.

#4 is the preferred style for a non-defining clause.

#3 is a combination that does not work well.