Consonant Ligatures
Clusters of two or more consonants form a ligature. Basically Oriya has two types of such consonant ligatures. The "northern" type is formed by fusion of two ore more consonants as in northern scripts like Devanāgarī (but to a lesser extent also in the Malayalam script in the south). In some instances the components can be easily identified, but sometimes completely new glyphs are formed. With the "southern" type the second component is reduced in size and put under the first as in the southern scripts used for Kannaḍa and Telugu (and to some extent also for Malayalam script). The following table shows the most commonly used ligatures. (Different fonts may use different ligatures.)
Read more about this topic: Oriya Alphabet