What is the difference between Apex Data Loader and Import Wizard as far as generating
extra accounts is concerned?

Answer: Apex Data Loader

Explanation:
If Salesforce account ID is specified incorrectly while loading contact, then loading of contact
fails as no account exists in Salesforce with this account ID. Import Wizard. If account name
is specified incorrectly while loading contact, then new account gets generated with the new
name.