I was just trying to find a way to run a query and compare the updated_at and created_at attributes of a record and came across this technique:
users = User.arel_table
User.where(users[:created_at].eq(users[:updated_at]))
It seems like .gt and .lt also work. While User.where("created_at = updated_at") would also work in SQL, we can use Arel to be database agnostic.