Lokey is right
Poly's spec and adv dips are for ppl who already have the
equivalent of local uni or full time poly dip. This explains
the shorter duration.
You are not required to undergo certain modules because u are
supposed to have acquired these knowledge. Hence the shorter
period.
Suppose u are a comp sc graduate n u wish to acquire specialised
knowldege in field such as network and IT security.
Suppose u are a chemical engring grad and u are working a
pharmaceutical company n u wish to acquire pharmaceutical
knowldege.
Say you are a diploma in business graduate from the poly. You
want to have a career change to work into the retail industry. You
go and take a specialist diploma in retail from the poly and after
graduate you go to apply for a retail supervisor/management trainee
job.
I think the chances of you getting employed is low because most
employers do not recognise your specialist diploma as its only a 1
year part time course