Auto cad designer- Applying Singapore EP

MoM does generally not recognise part-time degrees. Thus you will be treated as Non-degree holder and get an S-Pass, at best.

but I have ITI regular basic & please explain what is the difference between EP& S-PASS
MY EP they people already applied. so I got rejection from MOM otherwise they people suggest for S-pass & if EP application rejected then againi have to apply for S-PASS again it takes 4 to 5 week time.

A recognised (by MoM) university degree is precondition for EP. Part-time degrees are not recognised.
If you have only other technical certificates or a non-recognised degree, you can get an S-Pass instead.
The main difference (in your case) is that S-Pass incurs a levy your employer has to pay to the government, and that certain maximum foreigner quotas apply (to make sure locals are hired first).
In the application form (which is the same for both), the employer can indicate whether he wants an EP, S-Pass or "consider candidate for S-Pass if not eligible for EP". If this last option is NOT checked and your EP is rejected, you will not get an S-Pass either.

Edited to add: The offered salary (S$5500/month) is just above the threshold for bringing wife and kids along on Dependents Passes (DP), but it might not be enough to afford a reasonable lifestyle.

one more question .
I am not getting job in Singapore I am going there on deputation only for 2 years . then also such things are really matter means degree , full time part time etc etc.
& is it final that I am not getting EP in any case.according to my qualification . there is no any chance.
there is any problem for getting s-pass.
or is it good or not.

From a legal standpoint, it does not matter whether you are on deputation or not: You will live and work in Singapore and thus need an appropriate work visa.
An EP without university degree is possible for higher ranked positions (salary above S$12000/month).
You can use the SAT tool on the MoM website to figure out what you are eligible for.
But I guess in your case there isn't much difference (to you) in whether you have EP or S-Pass.

A last remark: With your many certificates and long work experience, the offered salary is too low. MoM also rejects work pass applications with insufficient salary!

how much the duration of S-PASS is it issue for 3 months only??
if I am the S-PASS holder than there is any salary restriction???
my company have to pay monthly basic on my behalf to government??
I am able to work easily like EP People work otherwise some difference is there???
in case of s-pass company have to show regarding my salary to government on monthly basic???

Work passes are usually issued for a year (if the employemnt contract is for a year or longer).
I do not understand what your other questions are about. Your employer must pay you the contractually agreed salary (without deductions) and in addition pay a levy to the government for employing you on S-Pass.
Further information about S-Pass is on the MoM website.