Difference between WD Blue and Black?

GeForce6

Honorable
May 30, 2012
65
0
10,640
Unsure which to get. I won't be getting an SSD so I thought I should at least get a premium HDD, but is a Black really that much better than a Blue, about £15 + a considerable time period worth? Amazon randomly raised the 500GB Black to £97 or something ridiculous, waiting for it to go back down to £67, or a WD Blue for £53. Both 500GB, 3.5", SATA 3.
 

GeForce6

Honorable
May 30, 2012
65
0
10,640
Deciding between a £70 WD Blue 1TB with 32MB Cache, or a £84 WD Black 1TB with 64MB cache. Is there much difference between the two, I mean a nice 64MB cache and dual processors on the Black, apparently it's only slightly faster than a Blue though and I'll probably find it difficult to convince my dad to let me buy a Black when he thought I was only buying a 500GB.