Diploma

It does not make much sense to do a BCA after you have completed a Diploma in architecture, unless you are interested in studying computer sciences and pursuing a career in the same field.
To improve your career prospects you need to study further either in your technical field or in a general area of study. If you wish to study further to improve your job prospects, then as a Diploma-holder, you can seek lateral entry to the second year of BE. Several engineering colleges offer this provision. You can pursue your Bachelors in architecture from Indian Institute of Architects (IIA) through correspondence. It conducts non-formal engineering education programs, successful completion of which is recognised as equivalent to a graduate degree in engineering. The Associate Membership of the Indian Institute of Architects (by examination) is at par with Bachelors Degree in Architecture of recognised Indian Universities as notified by the Government of India for the purpose of employment and services under Central government. In appropriate field.

Hi Vikas!
You can pursue a post-graduation Diploma in mass communication by applying to various colleges and giving their entrance exam. These colleges conduct a general aptitude test, after which your admission will be determined. Please refer to this link to find the best colleges in India offering a course in mass communication at post graduation level https://www.shiksha.com/mass-communication-media/articles/top-10-mass-communication-colleges-to-join-at-pg-level-blogId-8790
Speaking about the difference in Diploma and degree, both are quite different when it comes to course structure and importance in the hiring process. A degree is a 3-4 year course and has more detailed academic studies than a Diploma. A Diploma is more practical-centric and is of maximum 2 years' duration. When it comes to hiring, an employer will always give preference to a degree holder than a Diploma holder. Earning a degree opens more doors for opportunities as compared to Diploma. In fact, various career options also require at least a Bachelor degree.