Digitizing software, at its core, allows one to create the file that instructs an embroidery machine where and when to place stitches and execute machine functions to form a design. This was historically done one stitch at a time. Now, any modern digitizing software allows for the creation of shapes in an object-based method (like that used by vector graphics software) with the notable addition of embroidery-specific parameters applied on a shape-by-shape basis to fill each shape with stitches.
Digitizing software provides the tools not only to draw but to assign and visualize stitch types, stitch length, stitch angle, density, entry and exit points for each shape, and underlay, as well as more nuanced qualities that govern the look of a block of stitches and the behavior of the routines that fill shapes with them.
These software suites will almost always include advanced tools beyond those needed simply to draw shapes, assign stitches, and control machine commands such as organization, envelope distortion, template creation, shape manipulation, specialty stitch types, and embroidery-specific drawing tools. The addition of specialty tools is for controlling machine attachments, multimedia decoration, or even those that provide secondary business functions like decorated product visualization or job management.