What is the difference between structural designing and architecture ? what type of positions i can reach in both softwares ? which is best software?

Structural Engineering is a design of building,for example building base footings,column,beam,and slab are designed in the structural designing. Where as in architecture exterior part after structure is completed, after structure column,beam,slab on that structural elements we can design architectural look. 

You can be a good Senior Structural engineer,and a good Senior Architect Designer.

For Structural designing E-tabs is the best software.

For Architecture Revit Architecture is the best software.