---
- name: Install ntpd
  yum: name="{{item}}" state=installed
  with_items:
    - ntp
    - ntpdate
  when: ansible_distribution == 'CentOS'

- name: Enable ntpd
  service: name=ntpd enabled=yes state=started
  when: ansible_distribution == 'CentOS'

- name: Install ntpd
  apt: name="{{item}}" state=installed
  with_items:
    - ntp
    - ntpdate
  when: ansible_distribution == 'Debian' or ansible_distribution == 'Ubuntu'

- name: Enable ntpd
  service: name=ntp enabled=yes state=started
  when: ansible_distribution == 'Debian' or ansible_distribution == 'Ubuntu'
...