Somewhere I read that table should not be used for the layout purpose while creating a web-page. It was stated that table is used for classification of data. Now we see many website are using because it gives you great control over the layout of a web-page.
Although we can use layer, webmaster prefers table. Does this make any difference for SEO point of view.
Google certainly "could" validate pages if they want to -- but they have no reason to. For search engine purposes, the main reason to validate your mark-up is to make sure that there is no error that would cause part or all of your page to be skipped by the spider.
Does this make any difference for SEO point of view.
It can make a difference: pages that use many nested tables for layout have a lot of code compared to the amount of content, and search engines don't like this. If a page uses CSS and DIVs for layout instead, the page will have a much better "code to content ratio", which is something that search engines prefer.