It's up to the different makers of the tablets, not up to VIA. If you want a "low down" on the chipsets look here: VIA Technologies, Inc.
Otherwise, you just have to look at the tablet maker's specs for each tablet. They could all very well be the same, but marketing tries to make each look special. Any CPU has a range of operation, from a base in Mhz to a slight O/C.
I do not work for VIA, only a volunteer here. VIA never reads this Forum. In the Support section of the link I posted, you can try the "Contact Us" link, see what VIA says, if anything at all.
1)GA990XA-UD3, Phenom II 970 ,8Gb DDR3 1866, GTX670, 500Gb SATA II , LG DVD, Win 7 Ultimate 64bit
2) 970DE3/U3S3, Phenom II 955, 8Gb DDR3, GTX560Ti, DVDRW, Win 7 Ult.64 bit
3)AX78, Phenom 9600, GTX560Ti, 4Gb DDR2, Win 7 Ult.64bit
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