There are huge difference in concepts.
1. from Silktest Menu-> Option/Enable Extension &
2. from start/prorgram/borland/silktest/enable extension?
First one is applicable to project level. Second one is applicable machine level.
For example, Assume that your have IE6 browser and Google search is your application. From the second option, you disable IE extensions. Now you create a new project and enable IE6 extension to your browser. Silk can not identify any object as HTML objects.
To add any extension to your silktest project, It should be added in both places.
There one more difference w.r.t distributed testing...
if host & target machines are different then ...u have to enable the extension of all the target machine using 2nd method.....enabling extension through 1st method on host machine doesnt work for the target machines...