Inkscape is free. Illustrator costs hundreds of dollars. But Inkscape, compared to the latest version of Illustrator, is pretty limited in some ways. The menus are organized differently, and the shortcuts are different. Since Inkscape saves in SVG instead of a proprietary format, Inkscape is compatible with Adobe Illustrator 9 and better, with few limitations. It has some issues opening AI files but 99% of the time it works out OK.
This is a quick read for those looking to switch to Inkscape
Inkscape uses less RAM than Adobe products (in my experience) but really large, detailed files (some of my maps have as many as 10,000 objects) will cause the computer to lag.