A Life Peer is someone who has a noble title but it is not hereditary- the title does not automatically go to his heir when he dies.
A Hereditary Peer is someone who has a noble title but it is hereditary- the title will automatically go to his heir (typically his oldest son) upon his death.
The Lords Temporal are Peers (Life or Hereditary) who are sitting members of the House of Lords in Parliament.
The Lords Spiritual are high ranking bishops from the Anglican Church who also members of the House of Lords.
