The InterWeave integration is rather on the sophisticated side, but to bring this down to plain talk; it implements the Customers business process and work-flow with the data being brought back and forth from QuickBooks to Salesforce, and Salesforce to QuickBooks.
In regards to your request for information on the QODBC Connector, please see below.
Let’s first start with Who is FlexQuarters.
FLEXquarters.com Limited is an Intuit Partner that designs tools to automate connection and integration with your QuickBooks. This is the company who created the QODBC Driver (which is OEM’d by Intuit and is in your QuickBooks Desktop application right now). The distinction is that it is in “Read-Only” mode. The only function InterWeave does is upgrade your QODBC license to “Read/Write”, so InterWeave can read and create records in your QuickBooks.
This allows Read/Write communication now with your Salesforce and your QuickBooks.
For a technical definition, please see below.
What is QODBC?
QODBC is an ODBC driver (DLL) for QuickBooks format files. QuickBooks stores its data in its own proprietary DBMS file format. This driver allows users of any ODBC compliant front-end application to read and write data contained in QuickBooks format files similarly to any other ODBC enabled database.
QODBC works by accepting SQL commands from applications through the ODBC interface, then converting those calls to navigational XML commands to the QuickBooks DBMS and returning record sets that qualify for the query results. This driver is not a Client/Server product, but rather communicates directly with the QuickBooks application as it runs. QuickBooks is a flat file database, and this driver will not change it into a relational database, so keep that in mind when developing with this driver. QODBC acts as a ‘wrapper’ around the Intuit SDK so customers can finally get at their QuickBooks data using standard database tools, speeding development time.