Tablets are significantly larger than smartphones, and that's why they often have better reception. Also SAR ratings aren't as much of a worry since no one holds a tablet to their heads. But the difference between an 8 and 10 inch tablet isn't so much that it allows for a significantly different or longer antenna design. Power consumption is also an issue for both tablets and smartphones since they have smaller batteries and are rarely turned completely off, unlike laptops.
Motorola is a reception monster, and it still holds true that their tablet has a bit stronger signal than the Samsung.