The standard-library slices only implement the indexing operator []. BitSlice additionally implements the Boolean operators &, |, ^, and !.
The dyadic Boolean arithmetic operators all take any bitvec container as their second argument, and apply the operation in-place to the left-hand bit-slice. If the second argument exhausts before self does, then it is implicitly zero-extended. This means that &= zeros excess bits in self, while |= and ^= do not modify them.
The monadic operator ! inverts the entire bit-slice at once. Its API requires taking a &mut BitSlice reference and returning it, so you will need to structure your code accordingly.