Hardware Canucks - whats the difference between these two?

Hardware Canucks (http://www.hardwarecanucks.com/forum/)

- RAM (http://www.hardwarecanucks.com/forum/ram/)

- - whats the difference between these two? (http://www.hardwarecanucks.com/forum/ram/11459-whats-difference-between-these-two.html)

whats the difference between these two?

Corsair XMS2 Dominator TWIN2X4096-8500C5D 4GB 2X2GB PC2-8500 DDR2-1066 CL5-5-5-15 240PIN Memory Kit
NCIX.com - Buy Corsair XMS2 Dominator TWIN2X4096-8500C5D 4GB 2X2GB PC2-8500 DDR2-1066 CL5-5-5-15 240PIN Memory Kit - TWIN2X4096-8500C5D In Canada.

and

Corsair XMS2 Dominator TWIN2X4096-8500C5DF 4GB 2X2GB PC2-8500 DDR2-1066 CL5-5-5-15 240PIN Memory Kit
NCIX.com - Buy Corsair XMS2 Dominator TWIN2X4096-8500C5DF 4GB 2X2GB PC2-8500 DDR2-1066 CL5-5-5-15 240PIN Memory Kit - TWIN2X4096-8500C5DF In Canada.

i believe "F" means come with fan cooler...

google says the f means it comes with a fan :O

oh really? i chose first one since it was cheaper but I picked up the fans cooler along with it..guess I'll go for the second one.thanks for helping.