AutoCAD 2007/2008/2009 DWG Format

[#1]

what is the technical difference between drawing a rectangle with a line command or by a polyline command

[#2]

4-lines vs. one Pline.

[#3]

OP try the RECTANGLE command (or rec on the command line) and then explore the options that appear on the command line...

Dean is right. Either rectangle (rec) or polyline (pl) will give you a single closed object, whereas the line command (L) will give you 4 objects that appear to be a rectangle. A single object is easier to manipulate than 4 separate ones.

[#4]

When you need to extract information, such as slope, it's much easier to find with a line.

???

[#5]

...then explode the rectangle at that point is all. Otherwise...