I have a situation where I attempt to sweep a simple line and curve the geometry created is “tilted” when perpendicular to the grid.
When I use a copy and then skin it works well.
Most of the tuts seem to use sweep in this instance.
What is general practice and what are the differences in what it does and how it is used???
Thanks

Similar to your other question, ‘general practice’ really does depend on the use case. Sometimes too, there are historical reason (i.e. some node used to be super slow, or not support a certain type of geometry).

Re: copy vs sweep, only recently did sweep support attributes to set the scale/twist/roll as the cross section is swept along the curve. Why it works better in your situation, it's hard to tell without seeing the hip file. But ultimately, if it works for you, then great! If you post your hip file, maybe there's something going on that's making it not work as well as Copy + Skin?

And just as general advice: even if there might be a better way to do something, just getting used to a workflow is always good. Then later, you'll learn what might be better in some situations, worse in others, as you read the forums, observe coworkers, and look at other hip files. That's how it's been for me. For example, VOPs/Wrangles: for me, sometimes I find it easier to work in VOPs, other times wrangles. Some experienced artists will badger me when I use VOPs, telling me I'm slow and wrangles are better. While I'm grateful for their advice, sometimes I find VOPs work better as I work out a problem in my head. Other times Wrangles are better for me.