King Mongkut (King Rama IV) sought to give monastic life its former strictness, thus he founded a new movement within the Order and called it the Dhammayattika sect to distinguish it from the original Sangha, which was later called the Mahanikaya sect.
Time went on and both sects have changes and improvements so presently these two sects do not differ substantially in any way from each other. They all belong to Theravada and follow the conservative way of the study and practice of the disciplinary and doctrinal tenets. Both sects have the same Supreme Council of Ecclesiastical Administration presided over by His Holiness the Supreme Patriarch who may be appointed by His Majesty the King of Thailand. The Supreme Patriarch may belong to any sect as the case may be.