Diploma in Engineering is considered equivalent to 10+2 for admission in few undergraduate courses. However, there is a minimum eligibility condition for admission in each course which require a candidate to study required subjects and obtain required minimum marks in 10+2 or equivalent. For each BSc. programme too, there is a specific list of required one or more subjects(physics, chemistry, maths, biology, computer science, etc.) to be studied in 10+2. Hence, it may not be permissible for you to apply for BSc or such other courses in that case.
But, if your diploma programme is recognised as equivalent to 10+2 for the purpose of admission in BA/BCom/BSc by a particular university and you fulfill other eligibility criteria, then you can apply for the courses under that university. Check cut-off and minimum eligibility condition of different courses and other restrictions. We strictly advise you to consult university/colleges to know about allowed courses.
Courses you may be eligible for in some colleges:
BSc (Computer Science), BSc(Mechanical),
BCA, BBA, BBM, BCom, BA (few courses)
Courses you are eligible and can easily get in after completing diploma in engineering and which are more related to your qualification: