Dukes in the United Kingdom
Duke, in the United Kingdom, is the highest-ranking hereditary title in all four peerages of the British Isles. A duke thus outranks all other holders of titles of nobility (marquess, earl, viscount and baron).
Lord
The upper house of the Parliament of the United Kingdom is the House of Lords, which is an abbreviation of the full title, The Right Honourable the Lords Spiritual and Temporal in Parliament Assembled. The Lords Temporal are the people who are entitled to receive writs of summons to attend the House of Lords in right of a peerage. The Lords Spiritual are the Archbishops of Canterbury and York, the Bishops of London, Winchester and Durham, and the twenty-one longest-serving bishops of the Church of England from among the other bishops, who are all entitled to receive writs of summons in right of their bishoprics or archbishoprics.