Is there a difference between interior designing and interior architecture?

Yes, Interior designing involves more with colors, materials and finishing of a certain interior.
The Interior architecture is more about the spacing, measurements, figures and shapes of a certain interior.

define interior designing and define interior architecture....Architecture wide range of subject from concept to to the finish..interior designing..does it meant decoration?.

http://www.di.net/articles/the-gaps-between-interior-design-and-architecture/

Yes there is! Interior architecture is the initial design and space plan for use of structural boudaries and the human interaction within these boundaries.
Interior design is turning an interior space into an effective setting for the range of human activities that are to take place there.

Difference? both specialties are belong together...
interior designing evolves of combining materials , color , and its effect to catch the public interest and the customers curiosity - what are we offering for...
and what we can serve for..
While interior architecture is on how you create ,interpret the space planning, comfort, flexibility, shapes, as well adopting architectural colors, lighting effect and acoustics.
that may conclude into pleasant and uniqueness of your design fitted to the project as required.