what is the difference between normal site (version 3.00) without the instant search plugin
and a site with this plugin ?
i am asking because even without the plugin, there is an autocomplete, and i can see results while i type.
so what is the advantage of using this plugin ?
The Nop Instant Search plugin was released for nopCommerce 2.4 when there wasn't such search in nopCommerce. nopCommerce added this functionality in the later versions of nopCommerce. Even though there is a default autocomplete search in nopCommerce and both do the same job, we prefer to use the Nop Instant Search as it allows more settings in the administration, which makes it easier to manipulate for a store owner. For example with the Instant Search plugin you can change when the search results to appear i.e after typing at least 4 chars and also you can set the size of the images in the search results.
So it is up to you which one to use as a matter of personal preferences.
In summary - both do the same internally and give the same results and there are no performance differences but the Instant Search has more options in the administration and better visual styling(I personally think that it looks better).