vizcard,
If you use AP to enter the USA, you become a Parolee and are not in H1B status.
However, under the legacy Cronin Memo, if you were in H1B status before travelling and return to work for the same H1B employer, then not using the EAD for Employment Authorization will not be considered Unauthorized Employment as long as the H1B petition is valid.
You can return to H1B status either by:
a) Leaving the US and returning using a valid H1B visa.
b) If an H1B extension is approved (with I-94), then the Parole is terminated and you resume H1B status.
This
Murthy Memo explains it quite well.
The Cronin Memo can be found
here.