Interior Architecture Vs Interior Design

Source: jdninstitute.edu.in
People often mistake interior architecture and interior design to be the same, which in fact is a myth.
Interior architecture is the design of a building or shelter from inside out or the design of a new interior for a type of home that can be fixed. It can refer to the initial design and plan used for a building's interior, to that interior's later redesign made to accommodate a changed purpose, or to the significant revision of an original design for the adaptive reuse of the shell of the building concerned.
Whereas Interior design is the science and art of enhancing the interior of a building to achieve a healthier and more aesthetically pleasing environment for the people using the space.
Interior architecture includes not only the beauty and aesthetics of the space but also a lot about the technical aspects, the practicality of turning that into a breathable space and factors like plumbing, electricity, ventilation, etc.
Interior design deals majorly with the visual beauty accompanied along with soft furnishings and structural elements to enhance the output.

Source: jdinstitute.edu.in
However there are many similarities for both the job profiles, there are differences too. They are closely related, part of the same industry and of the same niche as well.
An interior architect takes up the project from the planning period whereas an interior designer starts his work usually after the structure is built.
The roles assigned to interior architects are quite fascinating.
Interior architects do design analysis and interior construction which requires a good amount of architectural knowledge.
Art of design, the science of architecture, and industrial design are the main areas of specification for an interior architect. They are even taught the magic of recreating the interior keeping the exterior intact and the same. Working as an interior architect is a lot more challenging on a daily basis as it requires great skills to effectively communicate with clients, to keep up the deadlines, produce ideas and design worth the construction and reconstruction.
The service expected from an interior designer goes beyond your expectation from an interior decorator. An interior designer should be really familiar with technical aspects too like one need to have a good hang of CAD software and more. Design services also include great communication ideas, creative presentation skills, effective implementation of technical tasks with specific detailings, and a lot more.
Some major tasks of an interior designer would include:
-Space planning
-Production of floor plans, elevations, 3D illustrations, working drawings to create a set of blueprints
-Lighting design
-Specialized designs: interior construction works, kitchen designs, storage solutions, bathrooms, and bedroom designs,
-Coordinating colour schemes
-Designs for custom furniture
(Source of info : dengarden)

Source: cf.Itkfcdn.net
A deeper technical knowledge of theories, concepts, and technical ability lists out the major difference between interior architecture and interior design. Both are extremely popular and grown fields though interior architecture gained all the praise in recent years.
“Good design doesn’t date.” – Harry Seidler