The difference filter can be used to compare differences between lists.

For example, the foo_list contains "pears" whereas the bar_list contains "oranges".

---
- hosts: localhost
  vars:
    foo_list: [ "apple", "banana", "grapes", "pears"]
    bar_list: [ "apple", "banana", "grapes", "oranges"]
  tasks:
  - name: foo_list differences
    debug:
      msg: "{{ foo_list | difference(bar_list) }}"

  - name: bar_list differences
    debug:
      msg: "{{ bar_list | difference(foo_list) }}"
...

Should produce the following.

TASK [foo_list differences] 
ok: [localhost] => {
    "msg": [
        "pears"
    ]
}

TASK [bar_list differences] 
ok: [localhost] => {
    "msg": [
        "oranges"
    ]
}