Why blackletter letters?

Version 7 of Unicode includes the following two letters:
ꬲ AB32 LATIN SMALL LETTER BLACKLETTER E
ꬽ AB3D LATIN SMALL LETTER BLACKLETTER O

There already were the following two:
𝔢 1D522 MATHEMATICAL FRAKTUR SMALL E
𝔬 1D52C MATHEMATICAL FRAKTUR SMALL O

For these, there’s an annotation:
     @ Fraktur symbols
     @+ This style is sometimes known as black-letter.

What’s the difference between U+AB32 and U+1D522?
Between U+AB3D and 1D52C?
Received on Tue Sep 10 2013 - 04:26:36 CDT