There are a few variations on how to lace. I believe Sheldon preferred trailing to be heads out while Shimano calls for the opposite. Machine built often end up with the flanges identical when viewed from the same side while hand built will look like mirror images. Supposedly it makes spoke insertion easier.
Anyhow, if build quality is otherwise OK (tension, wind-up, seating, stress relief etc) these differences tends to be marginal in terms of wheel performance and durability.