Currently I know:
About vertical micro programming: The control signals are not immediately passed to the ALU components, but are rather processed first and passed as an compressed function code.
About horizontal micro programming: There is just one wire connecting all ALU components directly. The signal contains for each component a bit indicating whether the component should be activated or not.
I guess H-$\mu$Programs generally runs faster as they have not to be processed extra. However have the disadvantage that the signals are pretty long.
Are there other advantages / disadvantages to each of these two types of micro programming?
EDIT: I saw a comment regarding the question being dated. Yes, it is. Nonetheless, examiners at university want to know such things. I had a hard time finding information, which is why I asked on this StackExchange, sort of as a last resort.