As anyone that has worked with SharePoint knows, there is next to zero correlation to what something is called in the SharePoint UI with what it is called in the SharePoint API. A lot of this is due to the fact that they changed the name for most everything between versions 2 and 3. This will be an ongoing post and I will add to it as I think of things.
| SharePoint UI Term | SharePoint API Class |
| Site Collection | SPSite |
| Site | SPWeb |
| Business Data Catalog | ApplicationRegistry |
| Site Column | SPField |
| Permission Level | SPRoleDefinition |
| Alternate Access Path | SPAlternateUrl |
| Top Level Site | RootWeb |
Think of something I am missing? Leave a comment so that I can get it added.