In my experience, tablets are less powerful.
The most expensive component of a device is the screen. So when there is a larger screen, often the chip and memory power is reduced, to keep the overall price down. This is not always the case, but it is common.
Here's a link comparing Galaxy Tab 7 with Galaxy S4. You can see the S4 has a 50% faster processor, much more memory, and better camera:
http://www.phonearena.com/phones/com...ones/7834,7597
Following Moore's law, next year's phone will be twice as fast and have more memory than this year's phone, for the same price.