Difference between originator of transaction and owner of the source fund
if Alice pay to Bob 0.1BTC, is that transaction signed by Alice?


Yes.

If I understand your quotation correctly, Andreas Antonopoulos is saying that Alice's personal assistant Charlie, could have prepared the transaction without any signature and passed it to Alice for approval and signing.

I don't know which wallets support this kind of arrangement. For most of us the preparation and signing are all handled together at the same time.