What responisiblities does an employer have towards Part-Time vs. Full-Time employees?

To the best of my knowledge, Labor Laws vary by state… so your best bet is to go to the website of your state’s Department if Labor.

State websites are usually:
www.state.(2-letter postal code).us
For example, New Jersey: www.state.NJ.us

Part Timers
You don’t have health insurance for part-timers.
You do not have to pay them vacation and sick time.
You can regulate their hours as needed up to 29 hours a week.

Full Timers
The opposite of the above.
Must put in a 40 hour work week.

No difference, except everyone must be treated equally (in Illinois)

In Alberta @hearkat has it right, no benefit plan is necessary for part-timers unless you are part of a strong and wonderful union.

@ChazMaz ; In a small business you don’t have to pay health insurance, sick, or vacation time either. I have never heard of any “law” that requires any employer regardless of size to provide those things. (And I live in California.) They are negotiated benefits, not rights of employment. Overtime laws are the same regardless of part time or full time status, and they do vary by state.

Other than state regulations (which are fairly minimal), the employer sets the policies and the hour levels at which they apply.

The responses above regarding benefits are generally correct, although some employers offer some part time employees some benefits.

It is not an issue of provision. It is an issue of having it available for them. I do not have to offer health care to the Part timers.

Part timers have no negotiation.

“Overtime laws are the same regardless of part time or full time status,”
Yes true, but keep their hours down and you will not have to worry about OT with the Part Timer.