1)SharePoint Deployment options :
1. You can generate solution package by creating WSP file. There are multiple ways for creating solution package like use WSPBuilder with your SharePoint solution or STSDEV utility for generating the WSP.
2. Once solution package (.wsp) is created either use STSADM command to deploy or upgrade the solution or you can upgrade or deploy from the Centeral Administration UI.
For more details please visit following some good links:
2) Solution files contains all the files which will be deployed on SharePoint front-end web server like User Controls(.ascx), Features files, Site Definition files (Onet.xml), resource (.resx) files, web part files(.webpart), stylesheets, java script files, Master pages, Page Layouts, aspx pages etc. All the files which are available in SharePoint 12 Hive.
3) DDF file is Data Definition File. This file is used when we manually generate the .wsp file. This file is a Text file which contains instructions required for MakeCab.exe utility.
4) Business Data Catalog is used to integrate the business data from from back-end applications like Siebel, Sap etc. in to MOSS 2007. Please refer following link for more details
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