Basically u need to understand the different architectures and technologies.

In web based techonolgy ie web add-in there are two or more technologies exists. ie mainly Java .net.

Note: In web addin we need to use either java addin or .net addin.

Basically in web addin it will recgoinse the browser and in .net addin it will recoginse the components which are developed by that technology.

Regards

Madhu D