The major difference into monocots and dicots are :
Monocot plants are those plants that contains a single cotyledon in its embryo.
Dicots plants are those that contains two cotyledons in its embryo.
Also , they differ in their root , root structure , stems , leaves , flowers and seeds.
Examples of Monocots are - Grass , rice , wheat , bamboo, bananas, corn etc..
Examples of dicots are - Roses, peas, oak trees, daisies , cacti and many more...