Below you can see the front view size comparison of Nikon D5500 and Canon 70D. Nikon D5500 is clearly the smaller of the two cameras. Its body is 15mm narrower, 7mm shorter and 9mm thinner than Canon 70D.
Nikon D5500 vs Canon 70D - Front View
Nikon D5500 vs Canon 70D - Top View
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.
Camera Size Comparison
Select Two Cameras for Size Comparison