avihimsa·sankappa and abyapada·sankappa

In samma·sankappa, we find abyapada·sankappa and
avihimsa·sankappa (besides nekkhamma·sankappa). I
still can't see why is there a need to include
avihimsa·sankappa. Shouldn't abyapada·sankappa cover it?

OR perhaps I'm not understanding these terms correctly.

Please enlighten.

mettâ,
kb