Not sure if this had been posted or not yet..
Example.. gmail shows 200 contacts your phone show 190..
A lot have said to do an import export, check for dups, show all contacts on phone under the hide feature.
What Ive found actually was that some of the contacts on the phone side had joined together under 1 contact. So instead of person 1, 2 and 3 reading as 3 seperate people under the list itself... person 2 and 3 have joined under person 1 under the contact list.. so therfore you still have 1,2 and 3 under gmail showing but NOT showing on your phone list itself.
Go through ALL of your phone contacts (I know, this sucks) and scroll down to see if there are any joined contacts. You can SPLIT them to unmerge.. youll show all the missing ones this way.
keywords: contacts, contact, merge, split, missing