Your problem appears to be a matter of scale. Your model is probably way smaller than the Autodesk model. When working with a character like in the Autodesk tutorial, first make sure your character is approximately real-world scale or at least scale similar to theirs. This matters quite a bit when making an initial Xgen description. It also matters for other areas such as certain shaders when rendering take scale into account, as do certain physics driven processes available in Maya.

For example, a human female could be around 165cm tall as measured in Maya. It can be anywhere close to this. (In fact it can actually be just about anything so long as you know this and are willing to tweak various Xgen attributes to compensate, etc.)

However a 2cm tall character will produce seemingly odd results compared to a tutorial that might assume the character is 200 cm tall. This is because things such as the density attributes and so forth when creating descriptions with Xgen are somewhat relative to scene units. They're not scene units, but they do take scene units into account. They also take surface parametrization into account. The more uniform the polygon spacing is - the better! To get results close to the Autodesk results you're going to have to scale your character to the same approximate world-space scale as theirs, which I'm guessing - and this is just a guess - is probably real-world scale or thereabouts.

Be aware you can scale the guides with the scale tool just as you would
ordinary geometry Place your guides first without concern for their scale. Then once they're placed select them in the Outliner and scale them appropriately. Then move on to modifying their shape to follow any contours you want, etc.

When scaling the guides they're easiest to select in the Outliner window via Window -> Outliner. Expand your collection and description and shift+select all of the guides at once. Select them all and uniformly scale them as appropriate for your model. Always remember to click the 'update' button in the XGen window. Otherwise your primitives may not match your guides. This can occur even when "auto update" is enabled.

If your scale isn't the same as theirs you will have to adjust your density and width attributes higher or lower to get a similar look. Attributes such as primitive length are relative to the guide lengths which is why we scale those first.

The size if your guides aren't going to automatically correspond for your mesh because Maya has no idea what your mesh is. To Maya, it's just a shape. It could just as easily be a be a mountain and you're making a forest or it could be a toothbrush. Maya can't tell the difference.

-Modulok-
I hope this helps some.

P.S. This forum indeed goes through cycles of a lot of crazy activity and then it's like a a great plague strikes and it's a ghost town. Nemirc and myself have seen it die and rebound several times.