Indecisive: One who has difficulty making a decision or sticking with that decision. This type may doubt themself or lack confidence in themself and will either find it difficult to make a decision, or will keep changing their mind once they do make a decision. They will generally hesitate before making any decision and may be significantly influenced by others, especially those who seem very self confident.
Decisive: The decisive person is one who does not hesitate when making a decision and is very confident in their ability to sort out information and act accordingly. Once they have made a decision, it will be hard to get them to change their mind unless very strong and convincing evidence can be presented to the contrary. They may be willing to make somewhat riskier decisions than the indecisive individual, especially if they have confidence in the source of the information on which they base the decision.