Increases in fascicle length (after eccentric training) will tend to cause the largest increases in muscle size distally (further from the body and closer to the extremities) while increases in fiber cross-sectional area (after concentric training) will tend to cause the largest increases in muscle size in the middle of the muscle. This means that the muscle will grow into a slightly different shape depending on whether eccentric-only or concentric-only training are done. How noticeable that is in reality is probably irrelevant except for high-level bodybuilders, in all honesty.