<p>What is the difference between the following types of endianness?</p>

<ul>
<li>byte (8b) invariant big and little endianness</li>
<li>half-word (16b) invariant big and little endianness</li>
<li>word (32b) invariant big and little endianness</li>
<li>double-word (64b) invariant big and little endianness</li>
</ul>

<p>Are there other types/variations?</p>

the basic concept is the ordering of bits:
```
```
1010 0011
```
```
in little-endian is the same as
```
```
0011 1010
```
```
in big-endian (and vice-versa).
You'll notice the order changes by grouping, not by individual bit.  I don't know of a system, for example, where
```
```
1100 0101
```
```
would be the "other-endian" version of the first version.