Regular Tessellation

According to Wikipedia:
A regular tessellation is a highly symmetric tessellation made up of congruent regular polygons Only three regular tessellations exist: those made up of equilateral triangles, squares, or hexagons. 

Semi-Regular Tessellations

Semi-regular tessellations are made up of different regular polygons. There are two properties of semi-regular tessellations: it is formed by regular polygons, and the arrangement of polygonsat every vertex angle is identical.

Irregular Tessellations