The C930 is the same as the C920 just slightly different colour I believe and usually more expensive. It might offer more software support for business applications, but I dont find that particularly relevant. Just vote for the C920 which is the consumer model.
Just be aware before voting for the business-oriented 930e, that it is not specifically designed for home usage (photo capturing, video recording, etc). It will perform these functions, no doubt, but was intended for conference video applications.