Now, I am confused here - One of my client's website got above 37,000 indexed pages in Google but if I see in Google webmaster tools where all of the sitemap xml have been submitted, I just got 10000 something pages has indexed. Why this variation, if somebody can help?
The answer is quite simple, google shows inaccurate information on purpose, just like with linkdomain: . No offense meant, but I don't think its fair to your customers to be selling SEO services and still not understand how basic search engine operators work.
Hay, google shows different indexed pages in google index and webmaster tools and it also show different backlinks in there index and webmaster tools so don't be confused,we can trust google search engine in indexed pages(LOL)
It means, if you have a customer getting SEO services from yourside, you will tell him that Google is showing inaccurate information for your site and your customer will be happy for your answer. You must know why Webmaster forums are meant for? For discussing our views, thoughts and updates with other members.
Any free tools that you're using on the web are not going to show the most accurate data possible. Unfortunately you're going to have to pay for a nice software suite to truly generate accurate results. Fortunately, that is a cost that you can incorporate into your services spread amongst all your clients. You shouldn't even feel it.
Try to check up to the last page of results. Maybe some of the pages are duplicates like what thanapa told.