Differences between T-hierarchy and E-hierarchy?

I have tried to make some difference among them but I am not satisfied with my learnings. I feel, that I am missing some concepts, and just mugging up.

Here is the information what I have collected till now-:

E-hierarchy-: 1) Used by Europeans.

2) Data rate is 2.048 Mbps.

3) E1 comprises 32 simultaneous channels.

4) Although, E1 has same frame interval 125 micro seconds a s T1,E1 transmits 256 bits.

T-hierarchy-: 1) Used by Americans and in Japan.

2) Data rate of T1 is 1.544 Mbps.

3) T1 comprises of 24 simultaneous channels.

4) But, T1 transmits 193 bits within the same interval.

If you don't want to explain, I would be happy to get some books to read about this. :)