There is a big difference between these two states, and they can have a powerful impact on the way organisations react to the decision maker.
Someone who is seen as decisive, but as yet undecided will be have the respect of others, who will usually assist in the process of coming to a decision in a positive manner.
By contrast, someone who is seen as indecisive, will be ignored, and work-arounds will be used to get things done, and at some time, if it is a personal trait, it needs to be removed from behavior patterns, or the individual will be removed.