Both B.Tech and BCA help the candidates to specialize in the field of Information Technology.

Comparison --

-B.Tech gives more indepth training in this field than a BCA course.
-Candidates pursuing BCA will need to complete MCA.
-In the corporate world MCA is treated more or less equivalent to the B.Tech course. -Both in terms of salary and career growth engineers reach heights faster than the BCA.
-Hence if given an option candidates should choose B.Tech over BCA.

Bachelors in Computer Application (BCA)
-The duration of the course is three years.
-It also gives an insight on how to manipulate the data of the computer.
-BCA course creates a foundation for those interested in this field.
-The course will give training in areas like

Languages – C, C++, Unix, JAVA etc
Database Management
Management Information System
Computer System Architecture
Operating System
Mathematics
Introduction to Microprocessor
Computer Graphics etc

Bachelors in Technology (B.Tech)
-It is a four year curriculum course.
-There are various specializations in this stream.
-In the field of IT there is CSE(Computer science engineering) and IT(information technology).

Other than this there are other specializations in this field too like—

Aeronautical Engineering
Architecture Engineering
Environmental Engineering
Fire Engineering
Genetic Engineering
Industrial & Production Engineering
Instrumentation Engineering
Marine Engineering
Civil Engineering
Communication Engineering
Electrical Engineering
Electronics Engineering
Automobile Engineering
Biomedical Engineering
Mining Engineering
Nuclear Engineering
Ocean Engineering
Petroleum Engineering
Textile Industry
Biotechnology Engineering
Broadcast Engineering
Chemical Engineering
Material Engineering
Mechanical Engineering
Metallurgical Engineering