Functional perspective:-
There is not much difference while Testing the Web & 
Desktop application with the functionality perspective.

Database testing:
The Database testing has to be emphasised in Web 
application as the architecuture is N-tier
where as Desktop application would be client-server 
arcitecture.

Non-functional perspective:- 
The security testing has to be emphasised in Web application
where as security testing would not be of much importance 
for Desktop application.

Regards,
Imthiyaz. Shaik