The 1872 Indian Head Cent (Penny) had two major varieties for the reverse of the coin and the one depicted above in the example image is the "Bold N" variety.

The difference between the "Shallow N" vs the "Bold N" Indian Head Cent has to do with the words "ONE CENT" on the back of the coin. The differences are actually fairly easy to make out and you should have no problem telling the difference after reading the following explanation:

The "Shallow N" variety used an older hub and die which resulted in a shallower "N"s in the words "ONE CENT". By "shallow" we mean that the N was 3-dimensionally shallow and almost blending in with the background as depicted by the white arrow in the example image below. In addition: The letter "E" had straighter "T" shaped serifs within them and the letters had larger notches as depicted by the arrows on the left side of the example image below.

The "Bold N" variety used a newer die and hub that would be used as the newer style on all later Indian pennies. This resulted in a deeper bolder "N" that didn't "sink" 3-dimensionally into the background. The letter "E" had triangular curved "trumpet" or "horn" shaped serifs and the notches on the letters were smaller. These features are depicted by the arrows on the right side of the example image of this penny below: