I am not sure what you mean by a vocational diploma vs. a regular high school diploma. That said, if your child is interested and finding success in a vocational area, by all means this is highly appropriate. We must not forget that young people are different in their interests and aptitudes and we must not lose sight that a vocational interest can be highly lucrative in the job world.
Certain students do well in math/science, some do well in English/history, and others do well in such interests as automotive repair, technology and other vocational interests.
It is not about comparing diplomas but helping young people be successful in their areas of interest and skills.
Your question got my attention and I'm wondering if you live in an area that there is a higher education high school?
In my area, we have our regular high schools where a student receives their high school diploma, but for students who qualify, we have a high school that goes through a local community college and upon completion the student not only acquires their high school diploma but they also receive a 2 year college degree. Is this what you are asking about?
I am also interested in this. I know that there is an application process and the student is required to compose an essay about their future plans and career choices. It is a small school, space is limited and they will only accept the best students with the highest grades and best charted behavior.
I understand that it is a lot of extra work placed on the student and there are no extra curricular activities, as the school feels that a student who is truly interested in a further education does not have time to be distracted by sports, cheering, or band.
I'm sure you have already realized the benefits, so if at all possible, I would choose the high school diploma that comes with a 2 year degree.
From there they can still pursue their college education, even if it's a different field of study. Extra credentials never hurt anyone.