i don't know what the real difference is. checking out amd official website, the specs are identical. same speed, cache, tdp, system bus, socket and 65nm process. i presuming that the difference is in architecture of the chip. since every other spec is the same, i'm assuming that the newer (RM) chip is going to be faster. either that or it's a case of rebranding.
from what i can read up right now, the chip performance is identical. the newer turion has more power states and can save more power @ idle. the memory has been upgraded to ddr2-800 and improved HT link
pretty much identical laptops to me. same chipsets (3200) hdmi, hd, 4gb vs 3gb ram is not an issue. they will perform the same except the acer will have better battery life. the best buy one has LED backlit screen.
i guess i'd go with the acer, bettery life seems to be only big difference.