Execution Context:

Siebel Server Scripts are executed in Siebel Application Servers by Application Object Manager (AOM).
Siebel Browser Scripts are executed at Client Side by Client Browser (Internet Explorer)

Files:

Siebel Browser Scripts are converted in JS (Java Script) files and stored in PUBLIC\ENU directory.
No JS files are created for Server Scripts and they are executing using Siebel Scripting [...]

We can invoke Smart Script from a button using “RunCallScript” method of an Applet. For Example on Applet_PreInvokeMethod below given line of code will invoke Smart Script named “Test SS”

Following are the differences between Internal and External Integration Objects