Two memtest sites?

Well we got this one http://www.memtest.org/
And we got this one http://www.memtest86.com/

What's the difference?
Which one to use, 3.2 or 1.40?

The first site is the original program, the second site is for the same basic program that some guys have "enhanced and updated" to include additional info, such as the motherboard chipset (865/875/nForce2) and other info, but they both work basically the same. Either one will test your memory for errors.

The second one only functions on x86 architecture systems.

Thanks