Disclaimer: This is not a legal advice.
But having gone through the GC process myself - simply applying for AOS (I-485) does not mean you have to use Advance Parole. If you still have H1B valid and stamped in the passport (I am not sure with other visas) - you can use the valid stamp to enter US legally. I have done so myself.
If however you have applied for AOS but have an expired visa stamp and are using EAD as the means to work here in the US - you need to apply for AP in advance of your departure and have it approved in advance of your departure.
Entering using AP is also a pain since you have to undergo a mandatory secondary inspection at port of entry.