Is the profile of a line, the same as straightness of a line in terms of GD&T?
‘Straightness’ can be a subjective term to define. In short, the profile of a line describes the ‘area of tolerance’ of the object.
gdandtbasics.com is a great resource for GD&T questions. Here’s the relevent article for your question: http://www.gdandtbasics.com/profile-of-a-line/
Does that help?