To display the same amount of content on different size devices you do not have to use the same amount of pixels, in general on tablet you can show the same content using many less pixels than on the high density phones.
Think about a balloon that you blow to 50% capacity (phone size) and draw 1 inch square on it, than blow it to 70% capacity (7 inch tablet). At this point your original square is much bigger. You could draw another 1 inch square that would be as easy to see, but you would use much less of balloon rubber to do that (less pixels). Blow up the balloon to 100% of the holding capacity and again the squares got bigger. If you use the same size area of content you will use less pixels on tablets, so exactly same size line of text could be 320px on 3 inch phone, 480px on new phone, 385px on the 7 inch tablet, and only 330px on 10 inch tablet.
Image shows EXACTLY the same user experience: from the left 10 inch tablet, 7 inch tablet, 4 inch phone, 3 inch phone.