There is a quite difference in pursuing degree(ba & bcom)  after diploma because those are of two different streams. Apply to degree courses after diploma unless and until you are interested in doing so. It would be better if you do first diploma in your interested stream and then pursue B.tech degree through entrance exams like ECET in the same stream. Engineering after 12th is also quite difficult but some subjects are connected and has content in depth. 

Hello,.
The differences are listed below:
Degree Vs. Diploma:

• A degree course is usually a 3 to 4 year long course conferred by a UGC-recognised university, after the completion of a course. An institute cannot confer a degree.A diploma is a short-term course, lasting 1 or 2 years, and is not necessarily given by a university. It could be conducted by an institute or polytechnic as well.Only a university can confer a degree. To pursue higher education, a degree from only a UGC approved university is accepted.An institute, a polytechnic or even a university can offer a diploma course. There is no need for the institute or the university to be UGC or AICTE approved.Typically, there is one subject that you major in, called the specialization whereas other subjects are called electives.A diploma is a specific academic award usually awarded for professional/vocational courses.A degree holder is preferred over a diploma holder in the same field.
• The relative importance of a diploma, when compared to a degree course is less.Degree programs give more in-depth knowledge and potentially start you at a higher level.

• Diploma programs provide education within your given field and get you into the work force sooner.

I hope this would help you. For further queries please feel free to write me down in the comment box.