Filter Query

[Evgeniy Strokin]

Hello,.. Lets say I have one query like this:
NAME:Smith
I need to restrict the result and I'm doing this:
NAME:Smith AND AGE:30
Also, I can do this using fq parameter:
q=NAME:Smith&fq=AGE:30
The result of second and third queries should be the same, right?
But why should I use fq then? In which cases this is better? Can you give me 
example to better understand the problem?
 
Thank you
Gene